diff --git a/clang/test/Driver/attr-availability-fuchsia.c b/clang/test/Driver/attr-availability-fuchsia.c
index 379a685d1a3f..c59a4f176c78 100644
--- a/clang/test/Driver/attr-availability-fuchsia.c
+++ b/clang/test/Driver/attr-availability-fuchsia.c
@@ -29,11 +29,11 @@
 // CHECK-ERROR: error: invalid integral value '16.0.0' in '-ffuchsia-api-level=16.0.0'
 
 #if __Fuchsia_API_level__ >= 16
-void f16() {
+void f16(void) {
 
 }
 #else
-void f15() {
+void f15(void) {
 
 }
 #endif
diff --git a/clang/test/Driver/cc-log-diagnostics.c b/clang/test/Driver/cc-log-diagnostics.c
index 069d2ad62922..c6c0afa2a1e2 100644
--- a/clang/test/Driver/cc-log-diagnostics.c
+++ b/clang/test/Driver/cc-log-diagnostics.c
@@ -4,7 +4,7 @@
 // RUN: %clang -Wfoobar -no-canonical-prefixes -target x86_64-apple-darwin10 -fsyntax-only %s
 // RUN: FileCheck %s < %t.log
 
-int f0() {}
+int f0(void) {}
 
 // CHECK: <dict>
 // CHECK:   <key>main-file</key>
@@ -27,7 +27,7 @@ int f0() {}
 // CHECK:       <key>line</key>
 // CHECK:       <integer>7</integer>
 // CHECK:       <key>column</key>
-// CHECK:       <integer>11</integer>
+// CHECK:       <integer>15</integer>
 // CHECK:       <key>message</key>
 // CHECK:       <string>non-void function does not return a value</string>
 // CHECK:     </dict>
diff --git a/clang/test/Driver/cl-options.c b/clang/test/Driver/cl-options.c
index 8d240e6e6e5c..50c2443c2189 100644
--- a/clang/test/Driver/cl-options.c
+++ b/clang/test/Driver/cl-options.c
@@ -772,4 +772,4 @@
 // FAKEDIR: "-libpath:/foo{{/|\\\\}}Lib{{/|\\\\}}10.0.12345.0{{/|\\\\}}ucrt
 // FAKEDIR: "-libpath:/foo{{/|\\\\}}Lib{{/|\\\\}}10.0.12345.0{{/|\\\\}}um
 
-void f() { }
+void f(void) { }
diff --git a/clang/test/Driver/cl-x86-flags.c b/clang/test/Driver/cl-x86-flags.c
index 8d7b74ffb87a..51b16f0ce354 100644
--- a/clang/test/Driver/cl-x86-flags.c
+++ b/clang/test/Driver/cl-x86-flags.c
@@ -133,5 +133,5 @@
 // tune: "-target-cpu" "sandybridge"
 // tune-SAME: "-tune-cpu" "haswell"
 
-void f() {
+void f(void) {
 }
diff --git a/clang/test/Driver/darwin-iphone-defaults.m b/clang/test/Driver/darwin-iphone-defaults.m
index fe50bbda5a50..ec9507fd091a 100644
--- a/clang/test/Driver/darwin-iphone-defaults.m
+++ b/clang/test/Driver/darwin-iphone-defaults.m
@@ -6,8 +6,8 @@
 // CHECK-NOT: msgSend_fixup_alloc
 // CHECK: OBJC_SELECTOR_REFERENCES
 
-int f0() {
-  return ^(){ return 0; }();
+int f0(void) {
+  return ^(void){ return 0; }();
 }
 
 @interface I0
@@ -22,7 +22,7 @@ int f0() {
 +(id) alloc;
 @end
 
-void f1() {
+void f1(void) {
   [I1 alloc];
 }
 
diff --git a/clang/test/Driver/debug-pass-structure.c b/clang/test/Driver/debug-pass-structure.c
index 5fde11e4d80d..8f75c00e8638 100644
--- a/clang/test/Driver/debug-pass-structure.c
+++ b/clang/test/Driver/debug-pass-structure.c
@@ -12,4 +12,4 @@
 
 // LEGACYPM: Pass Arguments:
 
-void f() {}
+void f(void) {}
diff --git a/clang/test/Driver/exceptions.m b/clang/test/Driver/exceptions.m
index 9b747bb84d19..51f1dd241bca 100644
--- a/clang/test/Driver/exceptions.m
+++ b/clang/test/Driver/exceptions.m
@@ -1,11 +1,11 @@
 // RUN: %clang -target x86_64-apple-darwin9 \
 // RUN:   -fsyntax-only -fno-exceptions %s
 
-void f1() {
+void f1(void) {
   @throw @"A";
 }
 
-void f0() {
+void f0(void) {
   @try {
     f1();
   } @catch (id x) {
@@ -13,7 +13,7 @@ void f0() {
   }
 }
 
-int main() {
+int main(void) {
   f0();
   return 0;
 }
diff --git a/clang/test/Driver/extract-api.c b/clang/test/Driver/extract-api.c
index f58d3a42ee24..4aba3ba9f61a 100644
--- a/clang/test/Driver/extract-api.c
+++ b/clang/test/Driver/extract-api.c
@@ -12,5 +12,5 @@
 // FIXME: Check for the dummy output now to verify that the custom action was executed.
 // RUN: %clang -extract-api %s | FileCheck -check-prefix DUMMY-OUTPUT %s
 
-void dummy_function();
+void dummy_function(void);
 // DUMMY-OUTPUT: dummy_function
diff --git a/clang/test/Driver/implicit-function-as-error.c b/clang/test/Driver/implicit-function-as-error.c
index d6309963ff73..9c45e2021245 100644
--- a/clang/test/Driver/implicit-function-as-error.c
+++ b/clang/test/Driver/implicit-function-as-error.c
@@ -5,7 +5,7 @@
 // For 64-bit iOS, automatically promote -Wimplicit-function-declaration
 // to an error.
 
-void radar_10894044() {
+void radar_10894044(void) {
   printf("Hi\n"); // expected-error {{implicitly declaring library function 'printf' with type 'int (const char *, ...)'}} expected-note {{include the header <stdio.h> or explicitly provide a declaration for 'printf'}}
   radar_10894044_not_declared(); // expected-error {{implicit declaration of function 'radar_10894044_not_declared' is invalid in C99}}
 }
diff --git a/clang/test/Driver/no-objc-arr.m b/clang/test/Driver/no-objc-arr.m
index 21246a37a6af..fba284f8bef1 100644
--- a/clang/test/Driver/no-objc-arr.m
+++ b/clang/test/Driver/no-objc-arr.m
@@ -2,7 +2,7 @@
 // expected-no-diagnostics
 // rdar://8949617
 
-void * FOO() {
+void * FOO(void) {
     id string = @"Hello World.\n";
     void *pointer = string; // No error must be issued
     return pointer;
diff --git a/clang/test/Driver/ppc-mprivileged-support-check.c b/clang/test/Driver/ppc-mprivileged-support-check.c
index 88b8103b79b1..85b7259908a1 100644
--- a/clang/test/Driver/ppc-mprivileged-support-check.c
+++ b/clang/test/Driver/ppc-mprivileged-support-check.c
@@ -17,7 +17,7 @@
 // RUN:   -mcpu=power7 -mprivileged %s 2>&1 | FileCheck %s --check-prefix=NOPRIV
 
 // __SP__ TODO: Fix this test case to check for the attribute.
-int test() {
+int test(void) {
   return 0;
 }
 
diff --git a/clang/test/Driver/ppc-p10-features-support-check.c b/clang/test/Driver/ppc-p10-features-support-check.c
index 20812552ee63..494514a9c1b9 100644
--- a/clang/test/Driver/ppc-p10-features-support-check.c
+++ b/clang/test/Driver/ppc-p10-features-support-check.c
@@ -38,7 +38,7 @@
 // RUN:   -mpcrel -mprefixed %s 2>&1 | FileCheck %s \
 // RUN:   --check-prefix=NOPCREL-PREFIX
 
-int test_p10_features() {
+int test_p10_features(void) {
   return 0;
 }
 
diff --git a/clang/test/Driver/redzone.c b/clang/test/Driver/redzone.c
index 7d6d42467952..1ab71716fe72 100644
--- a/clang/test/Driver/redzone.c
+++ b/clang/test/Driver/redzone.c
@@ -3,4 +3,4 @@
 // RUN: %clang -target i386-unknown-unknown -mred-zone %s -S -emit-llvm -o %t.log
 // RUN: grep -v 'noredzone' %t.log 
 
-int foo() { return 42; }
+int foo(void) { return 42; }
diff --git a/clang/test/Driver/riscv32-toolchain.c b/clang/test/Driver/riscv32-toolchain.c
index 3d03704a2b18..fb262a19a043 100644
--- a/clang/test/Driver/riscv32-toolchain.c
+++ b/clang/test/Driver/riscv32-toolchain.c
@@ -329,46 +329,46 @@ int size_a_ld = sizeof(_Atomic(long double));
 // Check types
 
 // CHECK: zeroext i8 @check_char()
-char check_char() { return 0; }
+char check_char(void) { return 0; }
 
 // CHECK: define dso_local signext i16 @check_short()
-short check_short() { return 0; }
+short check_short(void) { return 0; }
 
 // CHECK: define dso_local i32 @check_int()
-int check_int() { return 0; }
+int check_int(void) { return 0; }
 
 // CHECK: define dso_local i32 @check_wchar_t()
-int check_wchar_t() { return 0; }
+int check_wchar_t(void) { return 0; }
 
 // CHECK: define dso_local i32 @check_long()
-long check_long() { return 0; }
+long check_long(void) { return 0; }
 
 // CHECK: define dso_local i64 @check_longlong()
-long long check_longlong() { return 0; }
+long long check_longlong(void) { return 0; }
 
 // CHECK: define dso_local zeroext i8 @check_uchar()
-unsigned char check_uchar() { return 0; }
+unsigned char check_uchar(void) { return 0; }
 
 // CHECK: define dso_local zeroext i16 @check_ushort()
-unsigned short check_ushort() { return 0; }
+unsigned short check_ushort(void) { return 0; }
 
 // CHECK: define dso_local i32 @check_uint()
-unsigned int check_uint() { return 0; }
+unsigned int check_uint(void) { return 0; }
 
 // CHECK: define dso_local i32 @check_ulong()
-unsigned long check_ulong() { return 0; }
+unsigned long check_ulong(void) { return 0; }
 
 // CHECK: define dso_local i64 @check_ulonglong()
-unsigned long long check_ulonglong() { return 0; }
+unsigned long long check_ulonglong(void) { return 0; }
 
 // CHECK: define dso_local i32 @check_size_t()
-size_t check_size_t() { return 0; }
+size_t check_size_t(void) { return 0; }
 
 // CHECK: define dso_local float @check_float()
-float check_float() { return 0; }
+float check_float(void) { return 0; }
 
 // CHECK: define dso_local double @check_double()
-double check_double() { return 0; }
+double check_double(void) { return 0; }
 
 // CHECK: define dso_local fp128 @check_longdouble()
-long double check_longdouble() { return 0; }
+long double check_longdouble(void) { return 0; }
diff --git a/clang/test/Driver/riscv64-toolchain.c b/clang/test/Driver/riscv64-toolchain.c
index daa34a22e708..2774e004854c 100644
--- a/clang/test/Driver/riscv64-toolchain.c
+++ b/clang/test/Driver/riscv64-toolchain.c
@@ -285,46 +285,46 @@ int size_a_ld = sizeof(_Atomic(long double));
 // Check types
 
 // CHECK: define dso_local zeroext i8 @check_char()
-char check_char() { return 0; }
+char check_char(void) { return 0; }
 
 // CHECK: define dso_local signext i16 @check_short()
-short check_short() { return 0; }
+short check_short(void) { return 0; }
 
 // CHECK: define dso_local signext i32 @check_int()
-int check_int() { return 0; }
+int check_int(void) { return 0; }
 
 // CHECK: define dso_local signext i32 @check_wchar_t()
-int check_wchar_t() { return 0; }
+int check_wchar_t(void) { return 0; }
 
 // CHECK: define dso_local i64 @check_long()
-long check_long() { return 0; }
+long check_long(void) { return 0; }
 
 // CHECK: define dso_local i64 @check_longlong()
-long long check_longlong() { return 0; }
+long long check_longlong(void) { return 0; }
 
 // CHECK: define dso_local zeroext i8 @check_uchar()
-unsigned char check_uchar() { return 0; }
+unsigned char check_uchar(void) { return 0; }
 
 // CHECK: define dso_local zeroext i16 @check_ushort()
-unsigned short check_ushort() { return 0; }
+unsigned short check_ushort(void) { return 0; }
 
 // CHECK: define dso_local signext i32 @check_uint()
-unsigned int check_uint() { return 0; }
+unsigned int check_uint(void) { return 0; }
 
 // CHECK: define dso_local i64 @check_ulong()
-unsigned long check_ulong() { return 0; }
+unsigned long check_ulong(void) { return 0; }
 
 // CHECK: define dso_local i64 @check_ulonglong()
-unsigned long long check_ulonglong() { return 0; }
+unsigned long long check_ulonglong(void) { return 0; }
 
 // CHECK: define dso_local i64 @check_size_t()
-size_t check_size_t() { return 0; }
+size_t check_size_t(void) { return 0; }
 
 // CHECK: define dso_local float @check_float()
-float check_float() { return 0; }
+float check_float(void) { return 0; }
 
 // CHECK: define dso_local double @check_double()
-double check_double() { return 0; }
+double check_double(void) { return 0; }
 
 // CHECK: define dso_local fp128 @check_longdouble()
-long double check_longdouble() { return 0; }
+long double check_longdouble(void) { return 0; }
diff --git a/clang/test/Driver/types.c b/clang/test/Driver/types.c
index febce5c709ea..76823ad702b6 100644
--- a/clang/test/Driver/types.c
+++ b/clang/test/Driver/types.c
@@ -15,7 +15,7 @@
 // RUN: %clang -c --target=powerpc64-ibm-aix -fsyntax-only %s \
 // RUN: 2>&1
 
-void a() {
+void a(void) {
   __int128_t s;
   __uint128_t t;
 }
diff --git a/clang/test/Driver/x86-mgeneral-regs-only.c b/clang/test/Driver/x86-mgeneral-regs-only.c
index 35f96795eb9d..2d417bafb8a0 100644
--- a/clang/test/Driver/x86-mgeneral-regs-only.c
+++ b/clang/test/Driver/x86-mgeneral-regs-only.c
@@ -20,7 +20,7 @@
 // CMD: "-target-feature" "-sse"
 // CMD-AFTER: "-target-feature" "+avx2"
 
-void foo() { }
+void foo(void) { }
 
 // IR-GPR: attributes {{.*}} = { {{.*}} "target-features"="{{.*}}-avx{{.*}}-avx2{{.*}}-avx512f{{.*}}-sse{{.*}}-sse2{{.*}}-ssse3{{.*}}-x87{{.*}}"
 // IR-AVX2: attributes {{.*}} = { {{.*}} "target-features"="{{.*}}+avx{{.*}}+avx2{{.*}}+sse{{.*}}+sse2{{.*}}+ssse3{{.*}}-avx512f{{.*}}-x87{{.*}}"
diff --git a/clang/test/FixIt/auto-fixit.m b/clang/test/FixIt/auto-fixit.m
index d09f04c2b797..4d33ea30e21d 100644
--- a/clang/test/FixIt/auto-fixit.m
+++ b/clang/test/FixIt/auto-fixit.m
@@ -5,7 +5,7 @@
 
 // rdar://9036633
 
-int main() {
+int main(void) {
   auto int i = 0;
   return i;
 }
diff --git a/clang/test/FixIt/auto-isa-fixit.m b/clang/test/FixIt/auto-isa-fixit.m
index 3f22c1838ac0..5af90f52bdf3 100644
--- a/clang/test/FixIt/auto-isa-fixit.m
+++ b/clang/test/FixIt/auto-isa-fixit.m
@@ -6,7 +6,7 @@
 void object_setClass(id, id);
 Class object_getClass(id);
 
-id rhs();
+id rhs(void);
 
 Class pr6302(id x123) {
   x123->isa  = 0;
diff --git a/clang/test/FixIt/fixit-availability-maccatalyst.m b/clang/test/FixIt/fixit-availability-maccatalyst.m
index 3c370992c14d..2fa03d718ede 100644
--- a/clang/test/FixIt/fixit-availability-maccatalyst.m
+++ b/clang/test/FixIt/fixit-availability-maccatalyst.m
@@ -5,7 +5,7 @@ int function(void);
 
 void anotherFunction(int function);
 
-int use() {
+int use(void) {
   function();
 // CHECK: fix-it:{{.*}}:{[[@LINE-1]]:3-[[@LINE-1]]:3}:"if (@available(macCatalyst 13.2, *)) {\n      "
 // CHECK-NEXT: fix-it:{{.*}}:{[[@LINE-2]]:14-[[@LINE-2]]:14}:"\n  } else {\n      // Fallback on earlier versions\n  }"
diff --git a/clang/test/FixIt/fixit-availability.c b/clang/test/FixIt/fixit-availability.c
index 4b3c8a43920d..d21799635af2 100644
--- a/clang/test/FixIt/fixit-availability.c
+++ b/clang/test/FixIt/fixit-availability.c
@@ -3,7 +3,7 @@
 __attribute__((availability(macos, introduced=10.12)))
 int function(void);
 
-void use() {
+void use(void) {
   function();
 // CHECK: fix-it:{{.*}}:{[[@LINE-1]]:3-[[@LINE-1]]:3}:"if (__builtin_available(macOS 10.12, *)) {\n      "
 // CHECK-NEXT: fix-it:{{.*}}:{[[@LINE-2]]:14-[[@LINE-2]]:14}:"\n  } else {\n      // Fallback on earlier versions\n  }"
diff --git a/clang/test/FixIt/fixit-class-method-messaging.m b/clang/test/FixIt/fixit-class-method-messaging.m
index e2592d0c87f8..aa29b9c02061 100644
--- a/clang/test/FixIt/fixit-class-method-messaging.m
+++ b/clang/test/FixIt/fixit-class-method-messaging.m
@@ -11,7 +11,7 @@
 
 I* pi;
 
-I* foobar();
+I* foobar(void);
 
 @implementation I
 - (id) PrivInstMeth {
diff --git a/clang/test/FixIt/fixit-errors.c b/clang/test/FixIt/fixit-errors.c
index 1ac9d1c64320..a4dd263e0ad8 100644
--- a/clang/test/FixIt/fixit-errors.c
+++ b/clang/test/FixIt/fixit-errors.c
@@ -16,19 +16,19 @@ struct Point {
   float x, y, z;
 };
 
-struct Point *get_origin();
+struct Point *get_origin(void);
 
-void test_point() {
+void test_point(void) {
   (void)get_origin->x; // expected-error {{base of member reference is a function; perhaps you meant to call it with no arguments?}}
 }
 
 // These errors require C11.
 #if __STDC_VERSION__ > 199901L
-void noreturn_1() _Noreturn; // expected-error {{must precede function declarator}}
-void noreturn_1() {
+void noreturn_1(void) _Noreturn; // expected-error {{must precede function declarator}}
+void noreturn_1(void) {
   return; // expected-warning {{should not return}}
 }
-void noreturn_2() _Noreturn { // expected-error {{must precede function declarator}}
+void noreturn_2(void) _Noreturn { // expected-error {{must precede function declarator}}
   return; // expected-warning {{should not return}}
 }
 #endif
diff --git a/clang/test/FixIt/fixit-format-darwin.m b/clang/test/FixIt/fixit-format-darwin.m
index 54d25d92c2b3..f3981a7c0152 100644
--- a/clang/test/FixIt/fixit-format-darwin.m
+++ b/clang/test/FixIt/fixit-format-darwin.m
@@ -16,9 +16,9 @@ typedef int CFIndex;
 typedef int NSInteger;
 typedef unsigned int NSUInteger;
 #endif
-CFIndex getCFIndex();
-NSInteger getNSInteger();
-NSUInteger getNSUInteger();
+CFIndex getCFIndex(void);
+NSInteger getNSInteger(void);
+NSUInteger getNSUInteger(void);
 
 #define Log1(...) \
 do { \
@@ -37,7 +37,7 @@ do { \
   printf(X, Z); \
 } while (0) \
 
-void test() {
+void test(void) {
   printf("test 1: %s", getNSInteger()); 
   // CHECK: printf("test 1: %ld", (long)getNSInteger());
   printf("test 2: %s %s", getNSInteger(), getNSInteger());
@@ -71,14 +71,14 @@ do { \
   Outer1(__VA_ARGS__); Outer1(__VA_ARGS__); \
 } while (0)
 
-void bug33447() {
+void bug33447(void) {
   Outer2("test 8: %s", getNSInteger());  
   // CHECK: Outer2("test 8: %ld", (long)getNSInteger());
   Outer2("test 9: %s %s", getNSInteger(), getNSInteger());
   // CHECK: Outer2("test 9: %ld %ld", (long)getNSInteger(), (long)getNSInteger());
 }
 
-void testCFIndex() {
+void testCFIndex(void) {
   printf("test 10: %s", getCFIndex()); 
   // CHECK: printf("test 10: %ld", (long)getCFIndex());
   printf("test 11: %s %s", getCFIndex(), getCFIndex());
diff --git a/clang/test/FixIt/fixit-format-ios-nopedantic.m b/clang/test/FixIt/fixit-format-ios-nopedantic.m
index 0b332376c068..740a86bc82a1 100644
--- a/clang/test/FixIt/fixit-format-ios-nopedantic.m
+++ b/clang/test/FixIt/fixit-format-ios-nopedantic.m
@@ -4,10 +4,10 @@
 int printf(const char *restrict, ...);
 typedef unsigned int NSUInteger;
 typedef int NSInteger;
-NSUInteger getNSUInteger();
-NSInteger getNSInteger();
+NSUInteger getNSUInteger(void);
+NSInteger getNSInteger(void);
 
-void test() {
+void test(void) {
   // For thumbv7-apple-ios8.0.0 the underlying type of ssize_t is long
   // and the underlying type of size_t is unsigned long.
 
diff --git a/clang/test/FixIt/fixit-format-ios.m b/clang/test/FixIt/fixit-format-ios.m
index 9c3670d0c849..c4592c80042d 100644
--- a/clang/test/FixIt/fixit-format-ios.m
+++ b/clang/test/FixIt/fixit-format-ios.m
@@ -5,10 +5,10 @@
 int printf(const char * restrict, ...);
 typedef unsigned int NSUInteger;
 typedef int NSInteger;
-NSUInteger getNSUInteger();
-NSInteger getNSInteger();
+NSUInteger getNSUInteger(void);
+NSInteger getNSInteger(void);
 
-void test() {
+void test(void) {
   // For thumbv7-apple-ios8.0.0 the underlying type of ssize_t is long
   // and the underlying type of size_t is unsigned long.
 
diff --git a/clang/test/FixIt/fixit-multiple-selector-warnings.m b/clang/test/FixIt/fixit-multiple-selector-warnings.m
index 391728d0a9c1..4b9ff7b3a184 100644
--- a/clang/test/FixIt/fixit-multiple-selector-warnings.m
+++ b/clang/test/FixIt/fixit-multiple-selector-warnings.m
@@ -13,7 +13,7 @@
 - (id) compare: (id) arg1;
 @end
 
-SEL func()
+SEL func(void)
 {
         (void)@selector( compare: );
         (void)@selector (compare:);
diff --git a/clang/test/FixIt/fixit-newline-style.c b/clang/test/FixIt/fixit-newline-style.c
index c43eb3789e68..8c5f424c3987 100644
--- a/clang/test/FixIt/fixit-newline-style.c
+++ b/clang/test/FixIt/fixit-newline-style.c
@@ -5,7 +5,7 @@
 // CHECK: warning: unused label 'ddd'
 // CHECK-NEXT: {{^  ddd:}}
 // CHECK-NEXT: {{^  \^~~~$}}
-void f() {
+void f(void) {
   ddd:
   ;
 }
diff --git a/clang/test/FixIt/fixit-nsstring-compare.m b/clang/test/FixIt/fixit-nsstring-compare.m
index 6f0877c0590d..d74cee5cf157 100644
--- a/clang/test/FixIt/fixit-nsstring-compare.m
+++ b/clang/test/FixIt/fixit-nsstring-compare.m
@@ -10,7 +10,7 @@ typedef unsigned char BOOL;
 @interface NSString<NSObject>
 @end
 
-int main() {
+int main(void) {
   NSString *stringA = @"stringA";
 
   BOOL comparison = stringA==@"stringB";
diff --git a/clang/test/FixIt/fixit-objc.m b/clang/test/FixIt/fixit-objc.m
index 3e9ff605233b..756d0fcb62ba 100644
--- a/clang/test/FixIt/fixit-objc.m
+++ b/clang/test/FixIt/fixit-objc.m
@@ -10,7 +10,7 @@
 
 @protocol X;
 
-void foo() {
+void foo(void) {
   <X> *P;    // expected-warning{{protocol has no object type specified; defaults to qualified 'id'}}
 }
 
diff --git a/clang/test/FixIt/fixit-recursive-block.c b/clang/test/FixIt/fixit-recursive-block.c
index fec5b8028f90..eee6ec9a3687 100644
--- a/clang/test/FixIt/fixit-recursive-block.c
+++ b/clang/test/FixIt/fixit-recursive-block.c
@@ -4,8 +4,8 @@
 
 // rdar://10817031
 
-int main() {
-    void (^arc_fail)() = ^() {
+int main(void) {
+    void (^arc_fail)(void) = ^(void) {
 #ifdef ARC
 // expected-warning@-2 {{block pointer variable 'arc_fail' is null when captured by block}}
 #else
diff --git a/clang/test/FixIt/fixit-static-object-decl.m b/clang/test/FixIt/fixit-static-object-decl.m
index 5f4feada4905..6d6f55500518 100644
--- a/clang/test/FixIt/fixit-static-object-decl.m
+++ b/clang/test/FixIt/fixit-static-object-decl.m
@@ -19,12 +19,12 @@
 + (id) arrayWithObjects;
 @end
 
-NSArray func() {
+NSArray func(void) {
   NSArray P;
   return P;
 }
 
-NSArray (func2)() { return 0; }
+NSArray (func2)(void) { return 0; }
 
 #ifdef __cplusplus
 void test_result_type() {
@@ -32,6 +32,6 @@ void test_result_type() {
 }
 #endif
 
-int main() {
+int main(void) {
   	NSArray pluginNames = [NSArray arrayWithObjects];
 }
diff --git a/clang/test/FixIt/fixit-uninit.c b/clang/test/FixIt/fixit-uninit.c
index 853041e05b07..4993ea6ecda6 100644
--- a/clang/test/FixIt/fixit-uninit.c
+++ b/clang/test/FixIt/fixit-uninit.c
@@ -1,7 +1,7 @@
 // RUN: %clang_cc1 -fsyntax-only -Wuninitialized -verify %s
 // RUN: %clang_cc1 -fsyntax-only -Wuninitialized -fdiagnostics-parseable-fixits %s 2>&1 | FileCheck %s
 
-_Bool test_bool_no_false() {
+_Bool test_bool_no_false(void) {
   _Bool var; // expected-note {{initialize}}
   // CHECK: fix-it:"{{.*}}":{[[@LINE-1]]:12-[[@LINE-1]]:12}:" = 0"
   return var; // expected-warning {{uninitialized}}
@@ -10,13 +10,13 @@ _Bool test_bool_no_false() {
 #define bool _Bool
 #define false (bool)0
 #define true (bool)1
-bool test_bool_with_false() {
+bool test_bool_with_false(void) {
   bool var; // expected-note {{initialize}}
   // CHECK: fix-it:"{{.*}}":{[[@LINE-1]]:11-[[@LINE-1]]:11}:" = false"
   return var; // expected-warning {{uninitialized}}
 }
 
-bool test_bool_with_false_undefined() {
+bool test_bool_with_false_undefined(void) {
   bool
 #undef false
       var; // expected-note {{initialize}}
diff --git a/clang/test/FixIt/fixit.c b/clang/test/FixIt/fixit.c
index a46558c7fb0b..f94b1eff8a92 100644
--- a/clang/test/FixIt/fixit.c
+++ b/clang/test/FixIt/fixit.c
@@ -74,13 +74,13 @@ void removeUnusedLabels(char c) {
 }
 
 int oopsAComma = 0, // expected-error {{';'}}
-void oopsMoreCommas() {
+void oopsMoreCommas(void) {
   static int a[] = { 0, 1, 2 }, // expected-error {{';'}}
   static int b[] = { 3, 4, 5 }, // expected-error {{';'}}
   &a == &b ? oopsMoreCommas() : removeUnusedLabels(a[0]);
 }
 
-int commaAtEndOfStatement() {
+int commaAtEndOfStatement(void) {
   int a = 1;
   a = 5, // expected-error {{';'}}
   int m = 5, // expected-error {{';'}}
diff --git a/clang/test/FixIt/format-darwin.m b/clang/test/FixIt/format-darwin.m
index fcc81036fcf3..af2973668dc3 100644
--- a/clang/test/FixIt/format-darwin.m
+++ b/clang/test/FixIt/format-darwin.m
@@ -28,14 +28,14 @@ typedef enum NSIntegerEnum : NSInteger {
   EnumValueB
 } NSIntegerEnum;
 
-CFIndex getCFIndex();
-NSInteger getNSInteger();
-NSUInteger getNSUInteger();
-SInt32 getSInt32();
-UInt32 getUInt32();
-NSIntegerEnum getNSIntegerEnum();
+CFIndex getCFIndex(void);
+NSInteger getNSInteger(void);
+NSUInteger getNSUInteger(void);
+SInt32 getSInt32(void);
+UInt32 getUInt32(void);
+NSIntegerEnum getNSIntegerEnum(void);
 
-void testCorrectionInAllCases() {
+void testCorrectionInAllCases(void) {
   printf("%s", getNSInteger()); // expected-warning{{values of type 'NSInteger' should not be used as format arguments; add an explicit cast to 'long' instead}}
   printf("%s", getNSUInteger()); // expected-warning{{values of type 'NSUInteger' should not be used as format arguments; add an explicit cast to 'unsigned long' instead}}
   printf("%s", getSInt32()); // expected-warning{{values of type 'SInt32' should not be used as format arguments; add an explicit cast to 'int' instead}}
@@ -105,7 +105,7 @@ void testParens(Foo *obj, struct Bar *record) {
 
 #if __LP64__
 
-void testWarn() {
+void testWarn(void) {
   printf("%d", getNSInteger()); // expected-warning{{values of type 'NSInteger' should not be used as format arguments; add an explicit cast to 'long' instead}}
   printf("%u", getNSUInteger()); // expected-warning{{values of type 'NSUInteger' should not be used as format arguments; add an explicit cast to 'unsigned long' instead}}
   printf("%ld", getSInt32()); // expected-warning{{values of type 'SInt32' should not be used as format arguments; add an explicit cast to 'int' instead}}
@@ -134,7 +134,7 @@ void testWarn() {
   // CHECK-64: fix-it:"{{.*}}":{[[@LINE-3]]:16-[[@LINE-3]]:16}:"(long)"
 }
 
-void testPreserveHex() {
+void testPreserveHex(void) {
   printf("%x", getNSInteger()); // expected-warning{{values of type 'NSInteger' should not be used as format arguments; add an explicit cast to 'long' instead}}
   printf("%x", getNSUInteger()); // expected-warning{{values of type 'NSUInteger' should not be used as format arguments; add an explicit cast to 'unsigned long' instead}}
 
@@ -155,7 +155,7 @@ void testSignedness(NSInteger i, NSUInteger u) {
   // CHECK-64: fix-it:"{{.*}}":{[[@LINE-4]]:11-[[@LINE-4]]:13}:"%ld"
 }
 
-void testNoWarn() {
+void testNoWarn(void) {
   printf("%ld", getNSInteger()); // no-warning
   printf("%lu", getNSUInteger()); // no-warning
   printf("%d", getSInt32()); // no-warning
@@ -165,7 +165,7 @@ void testNoWarn() {
 
 #else
 
-void testWarn() {
+void testWarn(void) {
   printf("%ld", getNSInteger()); // expected-warning{{values of type 'NSInteger' should not be used as format arguments; add an explicit cast to 'long' instead}}
   printf("%lu", getNSUInteger()); // expected-warning{{values of type 'NSUInteger' should not be used as format arguments; add an explicit cast to 'unsigned long' instead}}
   printf("%d", getSInt32()); // expected-warning{{values of type 'SInt32' should not be used as format arguments; add an explicit cast to 'int' instead}}
@@ -185,7 +185,7 @@ void testWarn() {
   // CHECK-32: fix-it:"{{.*}}":{[[@LINE-2]]:17-[[@LINE-2]]:17}:"(long)"
 }
 
-void testPreserveHex() {
+void testPreserveHex(void) {
   printf("%lx", getNSInteger()); // expected-warning{{values of type 'NSInteger' should not be used as format arguments; add an explicit cast to 'long' instead}}
   printf("%lx", getNSUInteger()); // expected-warning{{values of type 'NSUInteger' should not be used as format arguments; add an explicit cast to 'unsigned long' instead}}
 
@@ -193,7 +193,7 @@ void testPreserveHex() {
   // CHECK-32: fix-it:"{{.*}}":{[[@LINE-3]]:17-[[@LINE-3]]:17}:"(unsigned long)"
 }
 
-void testNoWarn() {
+void testNoWarn(void) {
   printf("%d", getNSInteger()); // no-warning
   printf("%u", getNSUInteger()); // no-warning
   printf("%ld", getSInt32()); // no-warning
@@ -212,7 +212,7 @@ void testSignedness(NSInteger i, NSUInteger u) {
 #endif
 
 
-void testCasts() {
+void testCasts(void) {
   printf("%s", (NSInteger)0); // expected-warning{{values of type 'NSInteger' should not be used as format arguments; add an explicit cast to 'long' instead}}
   printf("%s", (NSUInteger)0); // expected-warning{{values of type 'NSUInteger' should not be used as format arguments; add an explicit cast to 'unsigned long' instead}}
   printf("%s", (SInt32)0); // expected-warning{{values of type 'SInt32' should not be used as format arguments; add an explicit cast to 'int' instead}}
@@ -241,7 +241,7 @@ void testCasts() {
   // CHECK: fix-it:"{{.*}}":{[[@LINE-3]]:16-[[@LINE-3]]:25}:"(long)"
 }
 
-void testCapitals() {
+void testCapitals(void) {
   printf("%D", 1); // expected-warning{{conversion specifier is not supported by ISO C}} expected-note {{did you mean to use 'd'?}}
   printf("%U", 1); // expected-warning{{conversion specifier is not supported by ISO C}} expected-note {{did you mean to use 'u'?}}
   printf("%O", 1); // expected-warning{{conversion specifier is not supported by ISO C}} expected-note {{did you mean to use 'o'?}}
diff --git a/clang/test/FixIt/format.m b/clang/test/FixIt/format.m
index af2d2ce797a4..966cf79b2e0f 100644
--- a/clang/test/FixIt/format.m
+++ b/clang/test/FixIt/format.m
@@ -177,7 +177,7 @@ void test_char(char c, signed char s, unsigned char u, uint8_t n) {
   // CHECK: fix-it:"{{.*}}":{[[@LINE-1]]:11-[[@LINE-1]]:15}:"%d"
 }
 
-void multichar_constants_false_negative() {
+void multichar_constants_false_negative(void) {
   // The value of a multi-character constant is implementation-defined, but
   // almost certainly shouldn't be printed with %c. However, the current
   // type-checker expects %c to correspond to an integer argument, because
@@ -188,7 +188,7 @@ void multichar_constants_false_negative() {
 }
 
 
-void test_percent_C() {
+void test_percent_C(void) {
   const unsigned short data = 'a';
   NSLog(@"%C", data);  // no-warning
 
@@ -233,7 +233,7 @@ void testSignedness(long i, unsigned long u) {
   // CHECK: fix-it:"{{.*}}":{[[@LINE-2]]:11-[[@LINE-2]]:14}:"%+ld"
 }
 
-void testSizeTypes() {
+void testSizeTypes(void) {
   printf("%zu", 0.f); // expected-warning-re{{format specifies type 'size_t' (aka '{{.+}}') but the argument has type 'float'}}
   // CHECK: fix-it:"{{.*}}":{[[@LINE-1]]:11-[[@LINE-1]]:14}:"%f"
 
@@ -260,7 +260,7 @@ typedef __PTRDIFF_TYPE__ ptrdiff_t;
                       short : (unsigned short)0,                               \
                       signed char : (unsigned char)0))
 
-void testPtrDiffTypes() {
+void testPtrDiffTypes(void) {
   __UNSIGNED_PTRDIFF_TYPE__ p1 = 0;
   printf("%tu", p1);  // No warning.
 
@@ -291,7 +291,7 @@ void testPtrDiffTypes() {
 #endif // !defined(__ANDROID__) && !defined(__Fuchsia__)
 }
 
-void testEnum() {
+void testEnum(void) {
   typedef enum {
     ImplicitA = 1,
     ImplicitB = 2
diff --git a/clang/test/FixIt/multiarg-selector-fixit.m b/clang/test/FixIt/multiarg-selector-fixit.m
index d60d31282ce7..39ffa5c13cc8 100644
--- a/clang/test/FixIt/multiarg-selector-fixit.m
+++ b/clang/test/FixIt/multiarg-selector-fixit.m
@@ -9,7 +9,7 @@
 - (void)testDataSource:(id)object withMultipleArguments:(id)arguments;
 @end
 
-int main() {
+int main(void) {
   id obj;
   [obj TestDataSource:nil withMultipleArguments:nil];
 }
diff --git a/clang/test/FixIt/no-macro-fixit.c b/clang/test/FixIt/no-macro-fixit.c
index b6a9285e22f0..8e1d400e5087 100644
--- a/clang/test/FixIt/no-macro-fixit.c
+++ b/clang/test/FixIt/no-macro-fixit.c
@@ -4,7 +4,7 @@
 #define va_arg(ap, type)    __builtin_va_arg(ap, type)
 typedef __builtin_va_list va_list;
 
-void myFunc() {
+void myFunc(void) {
     va_list values;
     
     int value;
diff --git a/clang/test/FixIt/objc-literals.m b/clang/test/FixIt/objc-literals.m
index 549cfde20250..dbed87b75733 100644
--- a/clang/test/FixIt/objc-literals.m
+++ b/clang/test/FixIt/objc-literals.m
@@ -35,7 +35,7 @@ typedef unsigned char BOOL;
 @interface NSString : NSObject
 @end
 
-void fixes() {
+void fixes(void) {
   id arr = @[
     17, // expected-error{{numeric literal must be prefixed by '@' in a collection}}
     'a', // expected-error{{character literal must be prefixed by '@'}}
diff --git a/clang/test/FixIt/property-access-fixit.m b/clang/test/FixIt/property-access-fixit.m
index 8623d29b9629..c0c1c4b0e279 100644
--- a/clang/test/FixIt/property-access-fixit.m
+++ b/clang/test/FixIt/property-access-fixit.m
@@ -22,7 +22,7 @@
 }
 @end
  
-int main()
+int main(void)
 {
     X *obj = [X new];
     obj.X = 3;
diff --git a/clang/test/FixIt/typo.c b/clang/test/FixIt/typo.c
index 4f4c67b538f2..295d2cbd45fa 100644
--- a/clang/test/FixIt/typo.c
+++ b/clang/test/FixIt/typo.c
@@ -29,7 +29,7 @@ struct Window window = {
   2.71818, 5.0, 6.0, Red
 };
 
-void test() {
+void test(void) {
   Rectangle r1; // expected-error{{must use 'struct' tag to refer to type 'Rectangle'}}
   // CHECK: fix-it:"{{.*}}":{[[@LINE-1]]:3-[[@LINE-1]]:3}:"struct "
   r1.top_left.x = 0;
diff --git a/clang/test/FixIt/typo.m b/clang/test/FixIt/typo.m
index 53afe7257d2a..5544eab05eb9 100644
--- a/clang/test/FixIt/typo.m
+++ b/clang/test/FixIt/typo.m
@@ -8,7 +8,7 @@
 + (int)method:(int)x;
 @end
 
-void test() {
+void test(void) {
   NSstring *str = @"A string"; // expected-error{{unknown type name 'NSstring'; did you mean 'NSString'?}}
 }
 
diff --git a/clang/test/Frontend/Inputs/SystemHeaderPrefix/line-directive-in-system.h b/clang/test/Frontend/Inputs/SystemHeaderPrefix/line-directive-in-system.h
index c4c15e58e4d7..a7902fcafd21 100644
--- a/clang/test/Frontend/Inputs/SystemHeaderPrefix/line-directive-in-system.h
+++ b/clang/test/Frontend/Inputs/SystemHeaderPrefix/line-directive-in-system.h
@@ -1,2 +1,2 @@
 #line 1 "foo.h"
-foo();
+foo(void);
diff --git a/clang/test/Frontend/Inputs/SystemHeaderPrefix/noline.h b/clang/test/Frontend/Inputs/SystemHeaderPrefix/noline.h
index a280f9a5cce6..7e6c37af261a 100644
--- a/clang/test/Frontend/Inputs/SystemHeaderPrefix/noline.h
+++ b/clang/test/Frontend/Inputs/SystemHeaderPrefix/noline.h
@@ -1 +1 @@
-foo();
+foo(void);
diff --git a/clang/test/Frontend/Inputs/absolute-paths.h b/clang/test/Frontend/Inputs/absolute-paths.h
index 5e682c734707..abcd0212cafb 100644
--- a/clang/test/Frontend/Inputs/absolute-paths.h
+++ b/clang/test/Frontend/Inputs/absolute-paths.h
@@ -1,3 +1,3 @@
-int f() {
+int f(void) {
   // Oops, no return.
 }
diff --git a/clang/test/Frontend/Inputs/line-directive.h b/clang/test/Frontend/Inputs/line-directive.h
index e05e9f51677e..446d1095cb61 100644
--- a/clang/test/Frontend/Inputs/line-directive.h
+++ b/clang/test/Frontend/Inputs/line-directive.h
@@ -1,2 +1,2 @@
 #line 10 "foo.h"
-foo(); // will warn if not treated as a system header
+foo(void); // will warn if not treated as a system header
diff --git a/clang/test/Frontend/Inputs/rewrite-includes-messages.h b/clang/test/Frontend/Inputs/rewrite-includes-messages.h
index e5f0eb251473..664bef429a10 100644
--- a/clang/test/Frontend/Inputs/rewrite-includes-messages.h
+++ b/clang/test/Frontend/Inputs/rewrite-includes-messages.h
@@ -1,4 +1,4 @@
-void f()
+void f(void)
 {
     int unused_variable;
 }
diff --git a/clang/test/Frontend/absolute-paths.c b/clang/test/Frontend/absolute-paths.c
index 07c81832ede4..619221384132 100644
--- a/clang/test/Frontend/absolute-paths.c
+++ b/clang/test/Frontend/absolute-paths.c
@@ -12,6 +12,6 @@
 
 // For files which don't exist, just print the filename.
 #line 123 "non-existant.c"
-int g() {}
-// NORMAL: non-existant.c:123:10: warning: non-void function does not return a value
-// ABSOLUTE: non-existant.c:123:10: warning: non-void function does not return a value
+int g(void) {}
+// NORMAL: non-existant.c:123:14: warning: non-void function does not return a value
+// ABSOLUTE: non-existant.c:123:14: warning: non-void function does not return a value
diff --git a/clang/test/Frontend/ast-codegen.c b/clang/test/Frontend/ast-codegen.c
index b45377850a23..53721a463217 100644
--- a/clang/test/Frontend/ast-codegen.c
+++ b/clang/test/Frontend/ast-codegen.c
@@ -9,5 +9,5 @@ __asm__("foo");
 int g0;
 
 // CHECK: define dso_local i32 @f0()
-int f0() {
+int f0(void) {
 }
diff --git a/clang/test/Frontend/ast-main.c b/clang/test/Frontend/ast-main.c
index 74e8bcf6db66..cdc74219f73a 100644
--- a/clang/test/Frontend/ast-main.c
+++ b/clang/test/Frontend/ast-main.c
@@ -3,6 +3,6 @@
 // RUN: env SDKROOT="/" %clang -emit-llvm -S -o %t2.ll -x ast - < %t.ast
 // RUN: diff %t1.ll %t2.ll
 
-int main() {
+int main(void) {
   return 0;
 }
diff --git a/clang/test/Frontend/backend-diagnostic.c b/clang/test/Frontend/backend-diagnostic.c
index e5dc4a6bacac..94431683fc8b 100644
--- a/clang/test/Frontend/backend-diagnostic.c
+++ b/clang/test/Frontend/backend-diagnostic.c
@@ -18,7 +18,7 @@ extern void doIt(char *);
 // REGULAR: warning: stack frame size ([[#]]) exceeds limit ([[#]]) in 'stackSizeWarning'
 // PROMOTE: error: stack frame size ([[#]]) exceeds limit ([[#]]) in 'stackSizeWarning'
 // IGNORE-NOT: stack frame size ([[#]]) exceeds limit ([[#]]) in 'stackSizeWarning'
-void stackSizeWarning() {
+void stackSizeWarning(void) {
   char buffer[80];
   doIt(buffer);
 }
diff --git a/clang/test/Frontend/embed-bitcode-noopt.c b/clang/test/Frontend/embed-bitcode-noopt.c
index b72f90bb015e..437be1187936 100644
--- a/clang/test/Frontend/embed-bitcode-noopt.c
+++ b/clang/test/Frontend/embed-bitcode-noopt.c
@@ -20,11 +20,11 @@
 // CHECK-BC-LABEL: attributes #0 = {{.*}} alwaysinline
 // CHECK-CMD: -O2
 
-__attribute__((always_inline)) void bar() {
+__attribute__((always_inline)) void bar(void) {
   return;
 }
 
-void foo() {
+void foo(void) {
   bar();
   return;
 }
diff --git a/clang/test/Frontend/fixed_point_add.c b/clang/test/Frontend/fixed_point_add.c
index d01989c5eab0..2629eb3428d7 100644
--- a/clang/test/Frontend/fixed_point_add.c
+++ b/clang/test/Frontend/fixed_point_add.c
@@ -36,7 +36,7 @@ _Bool b;
 // CHECK-NEXT:    store i16 [[TMP2]], i16* @sa, align 2
 // CHECK-NEXT:    ret void
 //
-void sadd_sasasa() {
+void sadd_sasasa(void) {
   sa = sa + sa;
 }
 
@@ -50,7 +50,7 @@ void sadd_sasasa() {
 // CHECK-NEXT:    store i32 [[TMP2]], i32* @a, align 4
 // CHECK-NEXT:    ret void
 //
-void sadd_asaa() {
+void sadd_asaa(void) {
   a = sa + a;
 }
 
@@ -63,7 +63,7 @@ void sadd_asaa() {
 // CHECK-NEXT:    store i16 [[TMP2]], i16* @sa, align 2
 // CHECK-NEXT:    ret void
 //
-void sadd_sasasf() {
+void sadd_sasasf(void) {
   sa = sa + sf;
 }
 
@@ -80,7 +80,7 @@ void sadd_sasasf() {
 // CHECK-NEXT:    store i16 [[RESIZE2]], i16* @sa, align 2
 // CHECK-NEXT:    ret void
 //
-void sadd_sasaf() {
+void sadd_sasaf(void) {
   sa = sa + f;
 }
 
@@ -94,7 +94,7 @@ void sadd_sasaf() {
 // CHECK-NEXT:    store i32 [[TMP2]], i32* @a, align 4
 // CHECK-NEXT:    ret void
 //
-void sadd_aasf() {
+void sadd_aasf(void) {
   a = a + sf;
 }
 
@@ -111,7 +111,7 @@ void sadd_aasf() {
 // CHECK-NEXT:    store i32 [[RESIZE2]], i32* @a, align 4
 // CHECK-NEXT:    ret void
 //
-void sadd_aalf() {
+void sadd_aalf(void) {
   a = a + lf;
 }
 
@@ -136,7 +136,7 @@ void sadd_aalf() {
 // UNSIGNED-NEXT:    store i16 [[TMP2]], i16* @sa, align 2
 // UNSIGNED-NEXT:    ret void
 //
-void sadd_sasausa() {
+void sadd_sasausa(void) {
   sa = sa + usa;
 }
 
@@ -163,7 +163,7 @@ void sadd_sasausa() {
 // UNSIGNED-NEXT:    store i32 [[TMP2]], i32* @a, align 4
 // UNSIGNED-NEXT:    ret void
 //
-void sadd_asaua() {
+void sadd_asaua(void) {
   a = sa + ua;
 }
 
@@ -189,7 +189,7 @@ void sadd_asaua() {
 // UNSIGNED-NEXT:    store i16 [[TMP2]], i16* @sa, align 2
 // UNSIGNED-NEXT:    ret void
 //
-void sadd_sasausf() {
+void sadd_sasausf(void) {
   sa = sa + usf;
 }
 
@@ -219,7 +219,7 @@ void sadd_sasausf() {
 // UNSIGNED-NEXT:    store i16 [[RESIZE2]], i16* @sa, align 2
 // UNSIGNED-NEXT:    ret void
 //
-void sadd_sasaulf() {
+void sadd_sasaulf(void) {
   sa = sa + ulf;
 }
 
@@ -235,7 +235,7 @@ void sadd_sasaulf() {
 // CHECK-NEXT:    store i32 [[TMP6]], i32* @a, align 4
 // CHECK-NEXT:    ret void
 //
-void sadd_aaaaa() {
+void sadd_aaaaa(void) {
   a = a + a2 + a3 + a4;
 }
 
@@ -248,7 +248,7 @@ void sadd_aaaaa() {
 // CHECK-NEXT:    store i16 [[TMP2]], i16* @usa, align 2
 // CHECK-NEXT:    ret void
 //
-void uadd_usausausa() {
+void uadd_usausausa(void) {
   usa = usa + usa;
 }
 
@@ -262,7 +262,7 @@ void uadd_usausausa() {
 // CHECK-NEXT:    store i32 [[TMP2]], i32* @ua, align 4
 // CHECK-NEXT:    ret void
 //
-void uadd_uausaua() {
+void uadd_uausaua(void) {
   ua = usa + ua;
 }
 
@@ -275,7 +275,7 @@ void uadd_uausaua() {
 // CHECK-NEXT:    store i16 [[TMP2]], i16* @usa, align 2
 // CHECK-NEXT:    ret void
 //
-void uadd_usausausf() {
+void uadd_usausausf(void) {
   usa = usa + usf;
 }
 
@@ -292,7 +292,7 @@ void uadd_usausausf() {
 // CHECK-NEXT:    store i16 [[RESIZE2]], i16* @usa, align 2
 // CHECK-NEXT:    ret void
 //
-void uadd_usausauf() {
+void uadd_usausauf(void) {
   usa = usa + uf;
 }
 
@@ -309,7 +309,7 @@ void uadd_usausauf() {
 // CHECK-NEXT:    store i16 [[RESIZE2]], i16* @sa, align 2
 // CHECK-NEXT:    ret void
 //
-void int_sasai() {
+void int_sasai(void) {
   sa = sa + i;
 }
 
@@ -325,7 +325,7 @@ void int_sasai() {
 // CHECK-NEXT:    store i16 [[RESIZE2]], i16* @sa, align 2
 // CHECK-NEXT:    ret void
 //
-void int_sasaui() {
+void int_sasaui(void) {
   sa = sa + ui;
 }
 
@@ -353,7 +353,7 @@ void int_sasaui() {
 // UNSIGNED-NEXT:    store i16 [[RESIZE2]], i16* @usa, align 2
 // UNSIGNED-NEXT:    ret void
 //
-void int_usausai() {
+void int_usausai(void) {
   usa = usa + i;
 }
 
@@ -381,7 +381,7 @@ void int_usausai() {
 // UNSIGNED-NEXT:    store i16 [[RESIZE2]], i16* @usa, align 2
 // UNSIGNED-NEXT:    ret void
 //
-void int_usausaui() {
+void int_usausaui(void) {
   usa = usa + ui;
 }
 
@@ -397,7 +397,7 @@ void int_usausaui() {
 // CHECK-NEXT:    store i32 [[RESIZE2]], i32* @lf, align 4
 // CHECK-NEXT:    ret void
 //
-void int_lflfui() {
+void int_lflfui(void) {
   lf = lf + ui;
 }
 
@@ -415,7 +415,7 @@ void int_lflfui() {
 // CHECK-NEXT:    store i32 [[RESIZE2]], i32* @a, align 4
 // CHECK-NEXT:    ret void
 //
-void int_aab() {
+void int_aab(void) {
   a = a + b;
 }
 
@@ -428,7 +428,7 @@ void int_aab() {
 // CHECK-NEXT:    store i16 [[TMP2]], i16* @sa_sat, align 2
 // CHECK-NEXT:    ret void
 //
-void sat_sassasas() {
+void sat_sassasas(void) {
   sa_sat = sa + sa_sat;
 }
 
@@ -450,7 +450,7 @@ void sat_sassasas() {
 // UNSIGNED-NEXT:    store i16 [[RESIZE1]], i16* @usa_sat, align 2
 // UNSIGNED-NEXT:    ret void
 //
-void sat_usasusausas() {
+void sat_usasusausas(void) {
   usa_sat = usa + usa_sat;
 }
 
@@ -476,7 +476,7 @@ void sat_usasusausas() {
 // UNSIGNED-NEXT:    store i32 [[RESIZE2]], i32* @ua_sat, align 4
 // UNSIGNED-NEXT:    ret void
 //
-void sat_uasuausas() {
+void sat_uasuausas(void) {
   ua_sat = ua + usa_sat;
 }
 
@@ -496,7 +496,7 @@ void sat_uasuausas() {
 // CHECK-NEXT:    store i16 [[RESIZE2]], i16* @sa_sat, align 2
 // CHECK-NEXT:    ret void
 //
-void sat_sassasi() {
+void sat_sassasi(void) {
   sa_sat = sa_sat + i;
 }
 
@@ -516,7 +516,7 @@ void sat_sassasi() {
 // CHECK-NEXT:    store i16 [[RESIZE2]], i16* @sa_sat, align 2
 // CHECK-NEXT:    ret void
 //
-void sat_sassasui() {
+void sat_sassasui(void) {
   sa_sat = sa_sat + ui;
 }
 
@@ -538,7 +538,7 @@ void sat_sassasui() {
 // UNSIGNED-NEXT:    store i16 [[RESIZE1]], i16* @uf_sat, align 2
 // UNSIGNED-NEXT:    ret void
 //
-void sat_ufsufsufs() {
+void sat_ufsufsufs(void) {
   uf_sat = uf_sat + uf_sat;
 }
 
@@ -574,6 +574,6 @@ void sat_ufsufsufs() {
 // UNSIGNED-NEXT:    store i16 [[RESIZE2]], i16* @usa_sat, align 2
 // UNSIGNED-NEXT:    ret void
 //
-void sat_usasusasi() {
+void sat_usasusasi(void) {
   usa_sat = usa_sat + i;
 }
diff --git a/clang/test/Frontend/fixed_point_comparisons.c b/clang/test/Frontend/fixed_point_comparisons.c
index 385d0c1352f3..2c2e3a2ad7a9 100644
--- a/clang/test/Frontend/fixed_point_comparisons.c
+++ b/clang/test/Frontend/fixed_point_comparisons.c
@@ -53,7 +53,7 @@ _Bool b_sne_true = 2.6hk != 2.6uhk;
 _Bool b_seq_true = 2.0hk == 2u;  // CHECK-DAG: @b_seq_true  = {{.*}}global i8 1, align 1
 _Bool b_seq_true2 = 2.0uhk == 2; // CHECK-DAG: @b_seq_true2 = {{.*}}global i8 1, align 1
 
-void TestComparisons() {
+void TestComparisons(void) {
   short _Accum sa;
   _Accum a;
   unsigned short _Accum usa;
@@ -132,7 +132,7 @@ void TestComparisons() {
   // CHECK-NEXT: {{.*}} = icmp ule i32 [[UPSCALE_A]], [[A2]]
 }
 
-void TestIntComparisons() {
+void TestIntComparisons(void) {
   short _Accum sa;
   unsigned short _Accum usa;
 
@@ -288,7 +288,7 @@ void TestIntComparisons() {
   // PADDED-NEXT: {{.*}} = icmp eq i39 [[RESIZE_A]], [[UPSCALE_I]]
 }
 
-void TestComparisonSignage() {
+void TestComparisonSignage(void) {
   short _Accum sa;
   unsigned short _Accum usa;
   int i;
@@ -327,7 +327,7 @@ void TestComparisonSignage() {
   // PADDED-NEXT: {{.*}} = icmp eq i39 [[RESIZE_A]], [[UPSCALE_I]]
 }
 
-void TestSaturationComparisons() {
+void TestSaturationComparisons(void) {
   short _Accum sa;
   _Accum a;
   _Sat short _Accum sat_sa;
@@ -361,7 +361,7 @@ void TestSaturationComparisons() {
   // PADDED-NEXT: {{.*}} = icmp eq i16 [[A]], [[A2]]
 }
 
-void StoreBooleanResult() {
+void StoreBooleanResult(void) {
   short _Accum sa;
   _Accum a;
   int res;
diff --git a/clang/test/Frontend/fixed_point_compound.c b/clang/test/Frontend/fixed_point_compound.c
index 5dcc7fba0da7..adf3aa903614 100644
--- a/clang/test/Frontend/fixed_point_compound.c
+++ b/clang/test/Frontend/fixed_point_compound.c
@@ -31,7 +31,7 @@ float fl;
 // CHECK-NEXT:    store i8 [[RESIZE1]], i8* @shf, align 1
 // CHECK-NEXT:    ret void
 //
-void add_shfa() {
+void add_shfa(void) {
   shf += a;
 }
 
@@ -57,7 +57,7 @@ void add_shfa() {
 // UNSIGNED-NEXT:    store i32 [[TMP2]], i32* @a, align 4
 // UNSIGNED-NEXT:    ret void
 //
-void add_auf() {
+void add_auf(void) {
   a += uf;
 }
 
@@ -73,7 +73,7 @@ void add_auf() {
 // CHECK-NEXT:    store i16 [[RESIZE1]], i16* @uf, align 2
 // CHECK-NEXT:    ret void
 //
-void add_ufula() {
+void add_ufula(void) {
   uf += ula;
 }
 
@@ -101,7 +101,7 @@ void add_ufula() {
 // UNSIGNED-NEXT:    store i64 [[TMP2]], i64* @ula, align 8
 // UNSIGNED-NEXT:    ret void
 //
-void add_ulashf() {
+void add_ulashf(void) {
   ula += shf;
 }
 
@@ -129,7 +129,7 @@ void add_ulashf() {
 // UNSIGNED-NEXT:    store i16 [[TMP2]], i16* @uf, align 2
 // UNSIGNED-NEXT:    ret void
 //
-void add_ufshf() {
+void add_ufshf(void) {
   uf += shf;
 }
 
@@ -143,7 +143,7 @@ void add_ufshf() {
 // CHECK-NEXT:    store i32 [[TMP2]], i32* @a, align 4
 // CHECK-NEXT:    ret void
 //
-void add_ashf() {
+void add_ashf(void) {
   a += shf;
 }
 
@@ -159,7 +159,7 @@ void add_ashf() {
 // CHECK-NEXT:    store i32 [[RESIZE2]], i32* @a, align 4
 // CHECK-NEXT:    ret void
 //
-void add_ai() {
+void add_ai(void) {
   a += i;
 }
 
@@ -175,7 +175,7 @@ void add_ai() {
 // CHECK-NEXT:    store i32 [[RESIZE2]], i32* @a, align 4
 // CHECK-NEXT:    ret void
 //
-void add_au() {
+void add_au(void) {
   a += u;
 }
 
@@ -201,7 +201,7 @@ void add_au() {
 // UNSIGNED-NEXT:    store i64 [[TMP2]], i64* @ula, align 8
 // UNSIGNED-NEXT:    ret void
 //
-void add_ulai() {
+void add_ulai(void) {
   ula += i;
 }
 
@@ -231,7 +231,7 @@ void add_ulai() {
 // UNSIGNED-NEXT:    store i32 [[RESIZE1]], i32* @i, align 4
 // UNSIGNED-NEXT:    ret void
 //
-void add_iula() {
+void add_iula(void) {
   i += ula;
 }
 
@@ -253,7 +253,7 @@ void add_iula() {
 // CHECK-NEXT:    store i8 [[RESIZE3]], i8* @c, align 1
 // CHECK-NEXT:    ret void
 //
-void add_ca() {
+void add_ca(void) {
   c += a;
 }
 
@@ -273,7 +273,7 @@ void add_ca() {
 // CHECK-NEXT:    store i32 [[RESIZE2]], i32* @sa, align 4
 // CHECK-NEXT:    ret void
 //
-void add_sai() {
+void add_sai(void) {
   sa += i;
 }
 
@@ -299,7 +299,7 @@ void add_sai() {
 // CHECK-NEXT:    store i8 [[RESIZE3]], i8* @c, align 1
 // CHECK-NEXT:    ret void
 //
-void add_csa() {
+void add_csa(void) {
   c += sa;
 }
 
@@ -325,7 +325,7 @@ void add_csa() {
 // UNSIGNED-NEXT:    store i64 [[RESIZE2]], i64* @sula, align 8
 // UNSIGNED-NEXT:    ret void
 //
-void add_sulau() {
+void add_sulau(void) {
   sula += u;
 }
 
@@ -356,7 +356,7 @@ void add_sulau() {
 // UNSIGNED-NEXT:    store i8 [[RESIZE1]], i8* @sshf, align 1
 // UNSIGNED-NEXT:    ret void
 //
-void add_sshsuf() {
+void add_sshsuf(void) {
   sshf += suf;
 }
 
@@ -372,7 +372,7 @@ void add_sshsuf() {
 // CHECK-NEXT:    store i32 [[TMP5]], i32* @a, align 4
 // CHECK-NEXT:    ret void
 //
-void add_afl() {
+void add_afl(void) {
   a += fl;
 }
 
@@ -386,7 +386,7 @@ void add_afl() {
 // CHECK-NEXT:    store float [[ADD]], float* @fl, align 4
 // CHECK-NEXT:    ret void
 //
-void add_fla() {
+void add_fla(void) {
   fl += a;
 }
 
@@ -402,7 +402,7 @@ void add_fla() {
 // CHECK-NEXT:    store i32 [[TMP5]], i32* @sa, align 4
 // CHECK-NEXT:    ret void
 //
-void add_safl() {
+void add_safl(void) {
   sa += fl;
 }
 
@@ -416,7 +416,7 @@ void add_safl() {
 // CHECK-NEXT:    store float [[ADD]], float* @fl, align 4
 // CHECK-NEXT:    ret void
 //
-void add_flsa() {
+void add_flsa(void) {
   fl += sa;
 }
 
@@ -445,7 +445,7 @@ void add_flsa() {
 // UNSIGNED-NEXT:    store i32 [[TMP2]], i32* @a, align 4
 // UNSIGNED-NEXT:    ret void
 //
-void sub_auf() {
+void sub_auf(void) {
   a -= uf;
 }
 
@@ -461,7 +461,7 @@ void sub_auf() {
 // CHECK-NEXT:    store i32 [[RESIZE2]], i32* @a, align 4
 // CHECK-NEXT:    ret void
 //
-void sub_ai() {
+void sub_ai(void) {
   a -= i;
 }
 
@@ -487,7 +487,7 @@ void sub_ai() {
 // CHECK-NEXT:    store i8 [[RESIZE3]], i8* @c, align 1
 // CHECK-NEXT:    ret void
 //
-void sub_csa() {
+void sub_csa(void) {
   c -= sa;
 }
 
@@ -503,7 +503,7 @@ void sub_csa() {
 // CHECK-NEXT:    store i32 [[TMP5]], i32* @a, align 4
 // CHECK-NEXT:    ret void
 //
-void sub_afl() {
+void sub_afl(void) {
   a -= fl;
 }
 
@@ -530,7 +530,7 @@ void sub_afl() {
 // UNSIGNED-NEXT:    store i32 [[TMP2]], i32* @a, align 4
 // UNSIGNED-NEXT:    ret void
 //
-void mul_auf() {
+void mul_auf(void) {
   a *= uf;
 }
 
@@ -546,7 +546,7 @@ void mul_auf() {
 // CHECK-NEXT:    store i32 [[RESIZE2]], i32* @a, align 4
 // CHECK-NEXT:    ret void
 //
-void mul_ai() {
+void mul_ai(void) {
   a *= i;
 }
 
@@ -572,7 +572,7 @@ void mul_ai() {
 // CHECK-NEXT:    store i8 [[RESIZE3]], i8* @c, align 1
 // CHECK-NEXT:    ret void
 //
-void mul_csa() {
+void mul_csa(void) {
   c *= sa;
 }
 
@@ -588,7 +588,7 @@ void mul_csa() {
 // CHECK-NEXT:    store i32 [[TMP5]], i32* @a, align 4
 // CHECK-NEXT:    ret void
 //
-void mul_afl() {
+void mul_afl(void) {
   a *= fl;
 }
 
@@ -615,7 +615,7 @@ void mul_afl() {
 // UNSIGNED-NEXT:    store i32 [[TMP2]], i32* @a, align 4
 // UNSIGNED-NEXT:    ret void
 //
-void div_auf() {
+void div_auf(void) {
   a /= uf;
 }
 
@@ -631,7 +631,7 @@ void div_auf() {
 // CHECK-NEXT:    store i32 [[RESIZE2]], i32* @a, align 4
 // CHECK-NEXT:    ret void
 //
-void div_ai() {
+void div_ai(void) {
   a /= i;
 }
 
@@ -657,7 +657,7 @@ void div_ai() {
 // CHECK-NEXT:    store i8 [[RESIZE3]], i8* @c, align 1
 // CHECK-NEXT:    ret void
 //
-void div_csa() {
+void div_csa(void) {
   c /= sa;
 }
 
@@ -673,7 +673,7 @@ void div_csa() {
 // CHECK-NEXT:    store i32 [[TMP5]], i32* @a, align 4
 // CHECK-NEXT:    ret void
 //
-void div_afl() {
+void div_afl(void) {
   a /= fl;
 }
 
@@ -686,7 +686,7 @@ void div_afl() {
 // CHECK-NEXT:    store i32 [[TMP2]], i32* @a, align 4
 // CHECK-NEXT:    ret void
 //
-void shft_ai() {
+void shft_ai(void) {
   a <<= i;
 }
 
@@ -708,7 +708,7 @@ void shft_ai() {
 // UNSIGNED-NEXT:    store i16 [[TMP3]], i16* @suf, align 2
 // UNSIGNED-NEXT:    ret void
 //
-void shft_sufi() {
+void shft_sufi(void) {
   suf <<= i;
 }
 
@@ -721,6 +721,6 @@ void shft_sufi() {
 // CHECK-NEXT:    store i64 [[TMP3]], i64* @ula, align 8
 // CHECK-NEXT:    ret void
 //
-void shft_ulai() {
+void shft_ulai(void) {
   ula >>= i;
 }
diff --git a/clang/test/Frontend/fixed_point_conversions.c b/clang/test/Frontend/fixed_point_conversions.c
index 96bc352d94dc..d7dcd26d05b6 100644
--- a/clang/test/Frontend/fixed_point_conversions.c
+++ b/clang/test/Frontend/fixed_point_conversions.c
@@ -41,7 +41,7 @@ double d;
 // CHECK-NEXT:    store i32 [[TMP0]], i32* @a2, align 4
 // CHECK-NEXT:    ret void
 //
-void fix_same1() {
+void fix_same1(void) {
   a2 = a;
 }
 
@@ -51,7 +51,7 @@ void fix_same1() {
 // CHECK-NEXT:    store i32 [[TMP0]], i32* @a2, align 4
 // CHECK-NEXT:    ret void
 //
-void fix_same2() {
+void fix_same2(void) {
   a2 = (_Accum)a;
 }
 
@@ -64,7 +64,7 @@ void fix_same2() {
 // CHECK-NEXT:    store i32 [[RESIZE]], i32* @a, align 4
 // CHECK-NEXT:    ret void
 //
-void fix_castdown1() {
+void fix_castdown1(void) {
   a = la;
 }
 
@@ -76,7 +76,7 @@ void fix_castdown1() {
 // CHECK-NEXT:    store i32 [[RESIZE]], i32* @a, align 4
 // CHECK-NEXT:    ret void
 //
-void fix_castdown2() {
+void fix_castdown2(void) {
   a = (_Accum)la;
 }
 
@@ -88,7 +88,7 @@ void fix_castdown2() {
 // CHECK-NEXT:    store i16 [[RESIZE]], i16* @sa, align 2
 // CHECK-NEXT:    ret void
 //
-void fix_castdown3() {
+void fix_castdown3(void) {
   sa = a;
 }
 
@@ -100,7 +100,7 @@ void fix_castdown3() {
 // CHECK-NEXT:    store i16 [[RESIZE]], i16* @sa, align 2
 // CHECK-NEXT:    ret void
 //
-void fix_castdown4() {
+void fix_castdown4(void) {
   sa = a;
 }
 
@@ -113,7 +113,7 @@ void fix_castdown4() {
 // CHECK-NEXT:    store i32 [[UPSCALE]], i32* @a, align 4
 // CHECK-NEXT:    ret void
 //
-void fix_castup1() {
+void fix_castup1(void) {
   a = sa;
 }
 
@@ -125,7 +125,7 @@ void fix_castup1() {
 // CHECK-NEXT:    store i32 [[UPSCALE]], i32* @a, align 4
 // CHECK-NEXT:    ret void
 //
-void fix_castup2() {
+void fix_castup2(void) {
   a = (_Accum)sa;
 }
 
@@ -137,7 +137,7 @@ void fix_castup2() {
 // CHECK-NEXT:    store i32 [[RESIZE]], i32* @a, align 4
 // CHECK-NEXT:    ret void
 //
-void fix_castup3() {
+void fix_castup3(void) {
   a = la;
 }
 
@@ -149,7 +149,7 @@ void fix_castup3() {
 // CHECK-NEXT:    store i32 [[RESIZE]], i32* @a, align 4
 // CHECK-NEXT:    ret void
 //
-void fix_castup4() {
+void fix_castup4(void) {
   a = (long _Accum)la;
 }
 
@@ -167,7 +167,7 @@ void fix_castup4() {
 // UNSIGNED-NEXT:    store i32 [[TMP0]], i32* @ua, align 4
 // UNSIGNED-NEXT:    ret void
 //
-void fix_sign1() {
+void fix_sign1(void) {
   ua = a;
 }
 
@@ -184,7 +184,7 @@ void fix_sign1() {
 // UNSIGNED-NEXT:    store i32 [[TMP0]], i32* @a, align 4
 // UNSIGNED-NEXT:    ret void
 //
-void fix_sign2() {
+void fix_sign2(void) {
   a = ua;
 }
 
@@ -201,7 +201,7 @@ void fix_sign2() {
 // UNSIGNED-NEXT:    store i32 [[TMP0]], i32* @ua, align 4
 // UNSIGNED-NEXT:    ret void
 //
-void fix_sign3() {
+void fix_sign3(void) {
   ua = (unsigned _Accum)a;
 }
 
@@ -218,7 +218,7 @@ void fix_sign3() {
 // UNSIGNED-NEXT:    store i32 [[TMP0]], i32* @a, align 4
 // UNSIGNED-NEXT:    ret void
 //
-void fix_sign4() {
+void fix_sign4(void) {
   a = (_Accum)ua;
 }
 
@@ -238,7 +238,7 @@ void fix_sign4() {
 // UNSIGNED-NEXT:    store i64 [[UPSCALE]], i64* @ula, align 8
 // UNSIGNED-NEXT:    ret void
 //
-void fix_sign5() {
+void fix_sign5(void) {
   ula = a;
 }
 
@@ -255,7 +255,7 @@ void fix_sign5() {
 // CHECK-NEXT:    store i16 [[RESIZE]], i16* @sat_sa, align 2
 // CHECK-NEXT:    ret void
 //
-void fix_sat1() {
+void fix_sat1(void) {
   // Casting down between types
   sat_sa = sat_a;
 }
@@ -272,7 +272,7 @@ void fix_sat1() {
 // CHECK-NEXT:    store i8 [[RESIZE]], i8* @sat_sf, align 1
 // CHECK-NEXT:    ret void
 //
-void fix_sat2() {
+void fix_sat2(void) {
   // Accum to Fract, decreasing scale
   sat_sf = sat_a;
 }
@@ -288,7 +288,7 @@ void fix_sat2() {
 // CHECK-NEXT:    store i16 [[RESIZE]], i16* @sat_f, align 2
 // CHECK-NEXT:    ret void
 //
-void fix_sat3() {
+void fix_sat3(void) {
   // Accum to Fract, same scale
   sat_f = a;
 }
@@ -306,7 +306,7 @@ void fix_sat3() {
 // CHECK-NEXT:    store i32 [[RESIZE1]], i32* @sat_lf, align 4
 // CHECK-NEXT:    ret void
 //
-void fix_sat4() {
+void fix_sat4(void) {
   // Accum to Fract, increasing scale
   sat_lf = sat_a;
 }
@@ -335,7 +335,7 @@ void fix_sat4() {
 // UNSIGNED-NEXT:    store i16 [[RESIZE]], i16* @sat_usa, align 2
 // UNSIGNED-NEXT:    ret void
 //
-void fix_sat5() {
+void fix_sat5(void) {
   // Signed to unsigned, decreasing scale
   sat_usa = sat_a;
 }
@@ -359,7 +359,7 @@ void fix_sat5() {
 // UNSIGNED-NEXT:    store i32 [[SATMIN]], i32* @sat_ua, align 4
 // UNSIGNED-NEXT:    ret void
 //
-void fix_sat6() {
+void fix_sat6(void) {
   // Signed to unsigned, increasing scale
   sat_ua = sat_a;
 }
@@ -370,7 +370,7 @@ void fix_sat6() {
 // CHECK-NEXT:    store i32 [[TMP0]], i32* @sat_a, align 4
 // CHECK-NEXT:    ret void
 //
-void fix_sat7() {
+void fix_sat7(void) {
   // Nothing when saturating to the same type and size
   sat_a = a;
 }
@@ -381,7 +381,7 @@ void fix_sat7() {
 // CHECK-NEXT:    store i32 [[TMP0]], i32* @a, align 4
 // CHECK-NEXT:    ret void
 //
-void fix_sat8() {
+void fix_sat8(void) {
   // Nothing when assigning back
   a = sat_a;
 }
@@ -393,7 +393,7 @@ void fix_sat8() {
 // CHECK-NEXT:    store i32 [[RESIZE]], i32* @sat_a, align 4
 // CHECK-NEXT:    ret void
 //
-void fix_sat9() {
+void fix_sat9(void) {
   // No overflow when casting from fract to signed accum
   sat_a = sat_f;
 }
@@ -418,7 +418,7 @@ void fix_sat9() {
 // UNSIGNED-NEXT:    store i32 [[SATMIN]], i32* @sat_ua, align 4
 // UNSIGNED-NEXT:    ret void
 //
-void fix_sat10() {
+void fix_sat10(void) {
   // Only get overflow checking if signed fract to unsigned accum
   sat_ua = sat_sf;
 }
@@ -432,7 +432,7 @@ void fix_sat10() {
 // CHECK-NEXT:    store i8 [[RESIZE]], i8* @sf, align 1
 // CHECK-NEXT:    ret void
 //
-void fix_fract1() {
+void fix_fract1(void) {
   // To lower scale
   sf = a;
 }
@@ -445,7 +445,7 @@ void fix_fract1() {
 // CHECK-NEXT:    store i32 [[UPSCALE]], i32* @a, align 4
 // CHECK-NEXT:    ret void
 //
-void fix_fract2() {
+void fix_fract2(void) {
   // To higher scale
   a = sf;
 }
@@ -457,7 +457,7 @@ void fix_fract2() {
 // CHECK-NEXT:    store i16 [[RESIZE]], i16* @f, align 2
 // CHECK-NEXT:    ret void
 //
-void fix_fract3() {
+void fix_fract3(void) {
   // To same scale
   f = a;
 }
@@ -469,7 +469,7 @@ void fix_fract3() {
 // CHECK-NEXT:    store i32 [[RESIZE]], i32* @a, align 4
 // CHECK-NEXT:    ret void
 //
-void fix_fract4() {
+void fix_fract4(void) {
   a = f;
 }
 
@@ -480,7 +480,7 @@ void fix_fract4() {
 // CHECK-NEXT:    store i32 [[RESIZE]], i32* @ua, align 4
 // CHECK-NEXT:    ret void
 //
-void fix_fract5() {
+void fix_fract5(void) {
   // To unsigned
   ua = uf;
 }
@@ -492,7 +492,7 @@ void fix_fract5() {
 // CHECK-NEXT:    store i16 [[RESIZE]], i16* @uf, align 2
 // CHECK-NEXT:    ret void
 //
-void fix_fract6() {
+void fix_fract6(void) {
   uf = ua;
 }
 
@@ -508,7 +508,7 @@ void fix_fract6() {
 // CHECK-NEXT:    store i32 [[RESIZE]], i32* @i, align 4
 // CHECK-NEXT:    ret void
 //
-void fix_int1() {
+void fix_int1(void) {
   // Will need to check for negative values
   i = sa;
 }
@@ -529,7 +529,7 @@ void fix_int1() {
 // UNSIGNED-NEXT:    store i32 [[RESIZE]], i32* @i, align 4
 // UNSIGNED-NEXT:    ret void
 //
-void fix_int2() {
+void fix_int2(void) {
   // No check needed for unsigned fixed points. Can just right shift.
   i = usa;
 }
@@ -543,7 +543,7 @@ void fix_int2() {
 // CHECK-NEXT:    store i16 [[UPSCALE]], i16* @sa, align 2
 // CHECK-NEXT:    ret void
 //
-void int_fix1() {
+void int_fix1(void) {
   sa = i;
 }
 
@@ -555,7 +555,7 @@ void int_fix1() {
 // CHECK-NEXT:    store i16 [[UPSCALE]], i16* @sa, align 2
 // CHECK-NEXT:    ret void
 //
-void int_fix2() {
+void int_fix2(void) {
   sa = ui;
 }
 
@@ -575,7 +575,7 @@ void int_fix2() {
 // UNSIGNED-NEXT:    store i16 [[UPSCALE]], i16* @usa, align 2
 // UNSIGNED-NEXT:    ret void
 //
-void int_fix3() {
+void int_fix3(void) {
   usa = i;
 }
 
@@ -595,7 +595,7 @@ void int_fix3() {
 // UNSIGNED-NEXT:    store i16 [[UPSCALE]], i16* @usa, align 2
 // UNSIGNED-NEXT:    ret void
 //
-void int_fix4() {
+void int_fix4(void) {
   usa = ui;
 }
 
@@ -607,7 +607,7 @@ void int_fix4() {
 // CHECK-NEXT:    store i64 [[UPSCALE]], i64* @la, align 8
 // CHECK-NEXT:    ret void
 //
-void int_fix5() {
+void int_fix5(void) {
   la = s;
 }
 
@@ -625,7 +625,7 @@ void int_fix5() {
 // CHECK-NEXT:    store i16 [[RESIZE1]], i16* @sat_sa, align 2
 // CHECK-NEXT:    ret void
 //
-void int_sat1() {
+void int_sat1(void) {
   sat_sa = i;
 }
 
@@ -640,7 +640,7 @@ void int_sat1() {
 // CHECK-NEXT:    store i16 [[RESIZE1]], i16* @sat_sa, align 2
 // CHECK-NEXT:    ret void
 //
-void int_sat2() {
+void int_sat2(void) {
   sat_sa = ui;
 }
 
@@ -670,7 +670,7 @@ void int_sat2() {
 // UNSIGNED-NEXT:    store i16 [[RESIZE1]], i16* @sat_usa, align 2
 // UNSIGNED-NEXT:    ret void
 //
-void int_sat3() {
+void int_sat3(void) {
   sat_usa = i;
 }
 
@@ -696,7 +696,7 @@ void int_sat3() {
 // UNSIGNED-NEXT:    store i16 [[RESIZE1]], i16* @sat_usa, align 2
 // UNSIGNED-NEXT:    ret void
 //
-void int_sat4() {
+void int_sat4(void) {
   sat_usa = ui;
 }
 
@@ -709,7 +709,7 @@ void int_sat4() {
 // CHECK-NEXT:    store i16 [[TMP2]], i16* @sa, align 2
 // CHECK-NEXT:    ret void
 //
-void float_fix1() {
+void float_fix1(void) {
   sa = fl;
 }
 
@@ -721,7 +721,7 @@ void float_fix1() {
 // CHECK-NEXT:    store i32 [[TMP2]], i32* @a, align 4
 // CHECK-NEXT:    ret void
 //
-void float_fix2() {
+void float_fix2(void) {
   a = fl;
 }
 
@@ -733,7 +733,7 @@ void float_fix2() {
 // CHECK-NEXT:    store i64 [[TMP2]], i64* @la, align 8
 // CHECK-NEXT:    ret void
 //
-void float_fix3() {
+void float_fix3(void) {
   la = fl;
 }
 
@@ -745,7 +745,7 @@ void float_fix3() {
 // CHECK-NEXT:    store i8 [[TMP2]], i8* @sf, align 1
 // CHECK-NEXT:    ret void
 //
-void float_fix4() {
+void float_fix4(void) {
   sf = fl;
 }
 
@@ -757,7 +757,7 @@ void float_fix4() {
 // CHECK-NEXT:    store i32 [[TMP2]], i32* @lf, align 4
 // CHECK-NEXT:    ret void
 //
-void float_fix5() {
+void float_fix5(void) {
   lf = fl;
 }
 
@@ -777,7 +777,7 @@ void float_fix5() {
 // UNSIGNED-NEXT:    store i32 [[TMP2]], i32* @ua, align 4
 // UNSIGNED-NEXT:    ret void
 //
-void float_fix6() {
+void float_fix6(void) {
   ua = fl;
 }
 
@@ -797,7 +797,7 @@ void float_fix6() {
 // UNSIGNED-NEXT:    store i16 [[TMP2]], i16* @uf, align 2
 // UNSIGNED-NEXT:    ret void
 //
-void float_fix7() {
+void float_fix7(void) {
   uf = fl;
 }
 
@@ -810,7 +810,7 @@ void float_fix7() {
 // CHECK-NEXT:    store float [[TMP2]], float* @fl, align 4
 // CHECK-NEXT:    ret void
 //
-void fix_float1() {
+void fix_float1(void) {
   fl = sa;
 }
 
@@ -822,7 +822,7 @@ void fix_float1() {
 // CHECK-NEXT:    store float [[TMP2]], float* @fl, align 4
 // CHECK-NEXT:    ret void
 //
-void fix_float2() {
+void fix_float2(void) {
   fl = a;
 }
 
@@ -834,7 +834,7 @@ void fix_float2() {
 // CHECK-NEXT:    store float [[TMP2]], float* @fl, align 4
 // CHECK-NEXT:    ret void
 //
-void fix_float3() {
+void fix_float3(void) {
   fl = la;
 }
 
@@ -846,7 +846,7 @@ void fix_float3() {
 // CHECK-NEXT:    store float [[TMP2]], float* @fl, align 4
 // CHECK-NEXT:    ret void
 //
-void fix_float4() {
+void fix_float4(void) {
   fl = sf;
 }
 
@@ -858,7 +858,7 @@ void fix_float4() {
 // CHECK-NEXT:    store float [[TMP2]], float* @fl, align 4
 // CHECK-NEXT:    ret void
 //
-void fix_float5() {
+void fix_float5(void) {
   fl = lf;
 }
 
@@ -878,7 +878,7 @@ void fix_float5() {
 // UNSIGNED-NEXT:    store float [[TMP2]], float* @fl, align 4
 // UNSIGNED-NEXT:    ret void
 //
-void fix_float6() {
+void fix_float6(void) {
   fl = ua;
 }
 
@@ -898,7 +898,7 @@ void fix_float6() {
 // UNSIGNED-NEXT:    store float [[TMP2]], float* @fl, align 4
 // UNSIGNED-NEXT:    ret void
 //
-void fix_float7() {
+void fix_float7(void) {
   fl = uf;
 }
 
@@ -911,7 +911,7 @@ void fix_float7() {
 // CHECK-NEXT:    store i16 [[TMP2]], i16* @sat_sa, align 2
 // CHECK-NEXT:    ret void
 //
-void float_sat1() {
+void float_sat1(void) {
   sat_sa = fl;
 }
 
@@ -923,7 +923,7 @@ void float_sat1() {
 // CHECK-NEXT:    store i32 [[TMP2]], i32* @sat_a, align 4
 // CHECK-NEXT:    ret void
 //
-void float_sat2() {
+void float_sat2(void) {
   sat_a = fl;
 }
 
@@ -935,7 +935,7 @@ void float_sat2() {
 // CHECK-NEXT:    store i64 [[TMP2]], i64* @sat_la, align 8
 // CHECK-NEXT:    ret void
 //
-void float_sat3() {
+void float_sat3(void) {
   sat_la = fl;
 }
 
@@ -947,7 +947,7 @@ void float_sat3() {
 // CHECK-NEXT:    store i8 [[TMP2]], i8* @sat_sf, align 1
 // CHECK-NEXT:    ret void
 //
-void float_sat4() {
+void float_sat4(void) {
   sat_sf = fl;
 }
 
@@ -969,7 +969,7 @@ void float_sat4() {
 // UNSIGNED-NEXT:    store i32 [[SATMIN]], i32* @sat_ua, align 4
 // UNSIGNED-NEXT:    ret void
 //
-void float_sat5() {
+void float_sat5(void) {
   sat_ua = fl;
 }
 
@@ -991,6 +991,6 @@ void float_sat5() {
 // UNSIGNED-NEXT:    store i16 [[SATMIN]], i16* @sat_uf, align 2
 // UNSIGNED-NEXT:    ret void
 //
-void float_sat6() {
+void float_sat6(void) {
   sat_uf = fl;
 }
diff --git a/clang/test/Frontend/fixed_point_conversions_half.c b/clang/test/Frontend/fixed_point_conversions_half.c
index 18261edf4474..7b84f2abe8d9 100644
--- a/clang/test/Frontend/fixed_point_conversions_half.c
+++ b/clang/test/Frontend/fixed_point_conversions_half.c
@@ -31,7 +31,7 @@ _Float16 h;
 // CHECK-NEXT:    store i8 [[TMP2]], i8* @sf, align 1
 // CHECK-NEXT:    ret void
 //
-void half_fix1() {
+void half_fix1(void) {
   sf = h;
 }
 
@@ -44,7 +44,7 @@ void half_fix1() {
 // CHECK-NEXT:    store i32 [[TMP3]], i32* @lf, align 4
 // CHECK-NEXT:    ret void
 //
-void half_fix2() {
+void half_fix2(void) {
   lf = h;
 }
 
@@ -56,7 +56,7 @@ void half_fix2() {
 // CHECK-NEXT:    store i16 [[TMP2]], i16* @sa, align 2
 // CHECK-NEXT:    ret void
 //
-void half_fix3() {
+void half_fix3(void) {
   sa = h;
 }
 
@@ -69,7 +69,7 @@ void half_fix3() {
 // CHECK-NEXT:    store i64 [[TMP3]], i64* @la, align 8
 // CHECK-NEXT:    ret void
 //
-void half_fix4() {
+void half_fix4(void) {
   la = h;
 }
 
@@ -90,7 +90,7 @@ void half_fix4() {
 // UNSIGNED-NEXT:    store i16 [[TMP2]], i16* @usa, align 2
 // UNSIGNED-NEXT:    ret void
 //
-void half_fix5() {
+void half_fix5(void) {
   usa = h;
 }
 
@@ -112,7 +112,7 @@ void half_fix5() {
 // UNSIGNED-NEXT:    store i64 [[TMP3]], i64* @ula, align 8
 // UNSIGNED-NEXT:    ret void
 //
-void half_fix6() {
+void half_fix6(void) {
   ula = h;
 }
 
@@ -125,7 +125,7 @@ void half_fix6() {
 // CHECK-NEXT:    store i8 [[TMP2]], i8* @sf_sat, align 1
 // CHECK-NEXT:    ret void
 //
-void half_sat1() {
+void half_sat1(void) {
   sf_sat = h;
 }
 
@@ -138,7 +138,7 @@ void half_sat1() {
 // CHECK-NEXT:    store i32 [[TMP3]], i32* @lf_sat, align 4
 // CHECK-NEXT:    ret void
 //
-void half_sat2() {
+void half_sat2(void) {
   lf_sat = h;
 }
 
@@ -150,7 +150,7 @@ void half_sat2() {
 // CHECK-NEXT:    store i16 [[TMP2]], i16* @sa_sat, align 2
 // CHECK-NEXT:    ret void
 //
-void half_sat3() {
+void half_sat3(void) {
   sa_sat = h;
 }
 
@@ -163,7 +163,7 @@ void half_sat3() {
 // CHECK-NEXT:    store i64 [[TMP3]], i64* @la_sat, align 8
 // CHECK-NEXT:    ret void
 //
-void half_sat4() {
+void half_sat4(void) {
   la_sat = h;
 }
 
@@ -186,7 +186,7 @@ void half_sat4() {
 // UNSIGNED-NEXT:    store i16 [[SATMIN]], i16* @usa_sat, align 2
 // UNSIGNED-NEXT:    ret void
 //
-void half_sat5() {
+void half_sat5(void) {
   usa_sat = h;
 }
 
@@ -210,7 +210,7 @@ void half_sat5() {
 // UNSIGNED-NEXT:    store i64 [[SATMIN]], i64* @ula_sat, align 8
 // UNSIGNED-NEXT:    ret void
 //
-void half_sat6() {
+void half_sat6(void) {
   ula_sat = h;
 }
 
@@ -223,7 +223,7 @@ void half_sat6() {
 // CHECK-NEXT:    store half [[TMP2]], half* @h, align 2
 // CHECK-NEXT:    ret void
 //
-void fix_half1() {
+void fix_half1(void) {
   h = sf;
 }
 
@@ -236,7 +236,7 @@ void fix_half1() {
 // CHECK-NEXT:    store half [[TMP3]], half* @h, align 2
 // CHECK-NEXT:    ret void
 //
-void fix_half2() {
+void fix_half2(void) {
   h = lf;
 }
 
@@ -248,7 +248,7 @@ void fix_half2() {
 // CHECK-NEXT:    store half [[TMP2]], half* @h, align 2
 // CHECK-NEXT:    ret void
 //
-void fix_half3() {
+void fix_half3(void) {
   h = sa;
 }
 
@@ -261,7 +261,7 @@ void fix_half3() {
 // CHECK-NEXT:    store half [[TMP3]], half* @h, align 2
 // CHECK-NEXT:    ret void
 //
-void fix_half4() {
+void fix_half4(void) {
   h = la;
 }
 
@@ -282,7 +282,7 @@ void fix_half4() {
 // UNSIGNED-NEXT:    store half [[TMP2]], half* @h, align 2
 // UNSIGNED-NEXT:    ret void
 //
-void fix_half5() {
+void fix_half5(void) {
   h = usa;
 }
 
@@ -304,6 +304,6 @@ void fix_half5() {
 // UNSIGNED-NEXT:    store half [[TMP3]], half* @h, align 2
 // UNSIGNED-NEXT:    ret void
 //
-void fix_half6() {
+void fix_half6(void) {
   h = ula;
 }
diff --git a/clang/test/Frontend/fixed_point_crash.c b/clang/test/Frontend/fixed_point_crash.c
index 869b7ee9355a..3b3911117400 100644
--- a/clang/test/Frontend/fixed_point_crash.c
+++ b/clang/test/Frontend/fixed_point_crash.c
@@ -5,13 +5,13 @@ union a {
   int i;
 };
 
-int fn1() {
+int fn1(void) {
   union a m;
   m.x = 5.6k;
   return m.i;
 }
 
-int fn2() {
+int fn2(void) {
   union a m;
   m.x = 7, 5.6k; // expected-warning {{expression result unused}}
   return m.x, m.i; // expected-warning {{left operand of comma operator has no effect}}
diff --git a/clang/test/Frontend/fixed_point_div.c b/clang/test/Frontend/fixed_point_div.c
index d54ba3bf48b0..ddb6b3941317 100644
--- a/clang/test/Frontend/fixed_point_div.c
+++ b/clang/test/Frontend/fixed_point_div.c
@@ -36,7 +36,7 @@ _Bool b;
 // CHECK-NEXT:    store i16 [[TMP2]], i16* @sa, align 2
 // CHECK-NEXT:    ret void
 //
-void sdiv_sasasa() {
+void sdiv_sasasa(void) {
   sa = sa / sa;
 }
 
@@ -50,7 +50,7 @@ void sdiv_sasasa() {
 // CHECK-NEXT:    store i32 [[TMP2]], i32* @a, align 4
 // CHECK-NEXT:    ret void
 //
-void sdiv_asaa() {
+void sdiv_asaa(void) {
   a = sa / a;
 }
 
@@ -63,7 +63,7 @@ void sdiv_asaa() {
 // CHECK-NEXT:    store i16 [[TMP2]], i16* @sa, align 2
 // CHECK-NEXT:    ret void
 //
-void sdiv_sasasf() {
+void sdiv_sasasf(void) {
   sa = sa / sf;
 }
 
@@ -80,7 +80,7 @@ void sdiv_sasasf() {
 // CHECK-NEXT:    store i16 [[RESIZE2]], i16* @sa, align 2
 // CHECK-NEXT:    ret void
 //
-void sdiv_sasaf() {
+void sdiv_sasaf(void) {
   sa = sa / f;
 }
 
@@ -94,7 +94,7 @@ void sdiv_sasaf() {
 // CHECK-NEXT:    store i32 [[TMP2]], i32* @a, align 4
 // CHECK-NEXT:    ret void
 //
-void sdiv_aasf() {
+void sdiv_aasf(void) {
   a = a / sf;
 }
 
@@ -111,7 +111,7 @@ void sdiv_aasf() {
 // CHECK-NEXT:    store i32 [[RESIZE2]], i32* @a, align 4
 // CHECK-NEXT:    ret void
 //
-void sdiv_aalf() {
+void sdiv_aalf(void) {
   a = a / lf;
 }
 
@@ -136,7 +136,7 @@ void sdiv_aalf() {
 // UNSIGNED-NEXT:    store i16 [[TMP2]], i16* @sa, align 2
 // UNSIGNED-NEXT:    ret void
 //
-void sdiv_sasausa() {
+void sdiv_sasausa(void) {
   sa = sa / usa;
 }
 
@@ -163,7 +163,7 @@ void sdiv_sasausa() {
 // UNSIGNED-NEXT:    store i32 [[TMP2]], i32* @a, align 4
 // UNSIGNED-NEXT:    ret void
 //
-void sdiv_asaua() {
+void sdiv_asaua(void) {
   a = sa / ua;
 }
 
@@ -189,7 +189,7 @@ void sdiv_asaua() {
 // UNSIGNED-NEXT:    store i16 [[TMP2]], i16* @sa, align 2
 // UNSIGNED-NEXT:    ret void
 //
-void sdiv_sasausf() {
+void sdiv_sasausf(void) {
   sa = sa / usf;
 }
 
@@ -219,7 +219,7 @@ void sdiv_sasausf() {
 // UNSIGNED-NEXT:    store i16 [[RESIZE2]], i16* @sa, align 2
 // UNSIGNED-NEXT:    ret void
 //
-void sdiv_sasaulf() {
+void sdiv_sasaulf(void) {
   sa = sa / ulf;
 }
 
@@ -235,7 +235,7 @@ void sdiv_sasaulf() {
 // CHECK-NEXT:    store i32 [[TMP6]], i32* @a, align 4
 // CHECK-NEXT:    ret void
 //
-void sdiv_aaaaa() {
+void sdiv_aaaaa(void) {
   a = a / a2 / a3 / a4;
 }
 
@@ -256,7 +256,7 @@ void sdiv_aaaaa() {
 // UNSIGNED-NEXT:    store i16 [[TMP2]], i16* @usa, align 2
 // UNSIGNED-NEXT:    ret void
 //
-void udiv_usausausa() {
+void udiv_usausausa(void) {
   usa = usa / usa;
 }
 
@@ -280,7 +280,7 @@ void udiv_usausausa() {
 // UNSIGNED-NEXT:    store i32 [[TMP2]], i32* @ua, align 4
 // UNSIGNED-NEXT:    ret void
 //
-void udiv_uausaua() {
+void udiv_uausaua(void) {
   ua = usa / ua;
 }
 
@@ -302,7 +302,7 @@ void udiv_uausaua() {
 // UNSIGNED-NEXT:    store i16 [[TMP2]], i16* @usa, align 2
 // UNSIGNED-NEXT:    ret void
 //
-void udiv_usausausf() {
+void udiv_usausausf(void) {
   usa = usa / usf;
 }
 
@@ -332,7 +332,7 @@ void udiv_usausausf() {
 // UNSIGNED-NEXT:    store i16 [[RESIZE2]], i16* @usa, align 2
 // UNSIGNED-NEXT:    ret void
 //
-void udiv_usausauf() {
+void udiv_usausauf(void) {
   usa = usa / uf;
 }
 
@@ -349,7 +349,7 @@ void udiv_usausauf() {
 // CHECK-NEXT:    store i16 [[RESIZE2]], i16* @sa, align 2
 // CHECK-NEXT:    ret void
 //
-void int_sasai() {
+void int_sasai(void) {
   sa = sa / i;
 }
 
@@ -365,7 +365,7 @@ void int_sasai() {
 // CHECK-NEXT:    store i16 [[RESIZE2]], i16* @sa, align 2
 // CHECK-NEXT:    ret void
 //
-void int_sasaui() {
+void int_sasaui(void) {
   sa = sa / ui;
 }
 
@@ -393,7 +393,7 @@ void int_sasaui() {
 // UNSIGNED-NEXT:    store i16 [[RESIZE2]], i16* @usa, align 2
 // UNSIGNED-NEXT:    ret void
 //
-void int_usausai() {
+void int_usausai(void) {
   usa = usa / i;
 }
 
@@ -421,7 +421,7 @@ void int_usausai() {
 // UNSIGNED-NEXT:    store i16 [[RESIZE2]], i16* @usa, align 2
 // UNSIGNED-NEXT:    ret void
 //
-void int_usausaui() {
+void int_usausaui(void) {
   usa = usa / ui;
 }
 
@@ -437,7 +437,7 @@ void int_usausaui() {
 // CHECK-NEXT:    store i32 [[RESIZE2]], i32* @lf, align 4
 // CHECK-NEXT:    ret void
 //
-void int_lflfui() {
+void int_lflfui(void) {
   lf = lf / ui;
 }
 
@@ -455,7 +455,7 @@ void int_lflfui() {
 // CHECK-NEXT:    store i32 [[RESIZE2]], i32* @a, align 4
 // CHECK-NEXT:    ret void
 //
-void int_aab() {
+void int_aab(void) {
   a = a / b;
 }
 
@@ -471,7 +471,7 @@ void int_aab() {
 // CHECK-NEXT:    store i32 [[RESIZE2]], i32* @a, align 4
 // CHECK-NEXT:    ret void
 //
-void int_aia() {
+void int_aia(void) {
   a = i / a;
 }
 
@@ -499,7 +499,7 @@ void int_aia() {
 // UNSIGNED-NEXT:    store i16 [[RESIZE2]], i16* @usa, align 2
 // UNSIGNED-NEXT:    ret void
 //
-void int_usauiusa() {
+void int_usauiusa(void) {
   usa = ui / usa;
 }
 
@@ -515,7 +515,7 @@ void int_usauiusa() {
 // CHECK-NEXT:    store i16 [[RESIZE2]], i16* @sa, align 2
 // CHECK-NEXT:    ret void
 //
-void int_sauisa() {
+void int_sauisa(void) {
   sa = ui / sa;
 }
 
@@ -528,7 +528,7 @@ void int_sauisa() {
 // CHECK-NEXT:    store i16 [[TMP2]], i16* @sa_sat, align 2
 // CHECK-NEXT:    ret void
 //
-void sat_sassasas() {
+void sat_sassasas(void) {
   sa_sat = sa / sa_sat;
 }
 
@@ -550,7 +550,7 @@ void sat_sassasas() {
 // UNSIGNED-NEXT:    store i16 [[RESIZE1]], i16* @usa_sat, align 2
 // UNSIGNED-NEXT:    ret void
 //
-void sat_usasusausas() {
+void sat_usasusausas(void) {
   usa_sat = usa / usa_sat;
 }
 
@@ -576,7 +576,7 @@ void sat_usasusausas() {
 // UNSIGNED-NEXT:    store i32 [[RESIZE2]], i32* @ua_sat, align 4
 // UNSIGNED-NEXT:    ret void
 //
-void sat_uasuausas() {
+void sat_uasuausas(void) {
   ua_sat = ua / usa_sat;
 }
 
@@ -596,7 +596,7 @@ void sat_uasuausas() {
 // CHECK-NEXT:    store i16 [[RESIZE2]], i16* @sa_sat, align 2
 // CHECK-NEXT:    ret void
 //
-void sat_sassasi() {
+void sat_sassasi(void) {
   sa_sat = sa_sat / i;
 }
 
@@ -616,7 +616,7 @@ void sat_sassasi() {
 // CHECK-NEXT:    store i16 [[RESIZE2]], i16* @sa_sat, align 2
 // CHECK-NEXT:    ret void
 //
-void sat_sassasui() {
+void sat_sassasui(void) {
   sa_sat = sa_sat / ui;
 }
 
@@ -638,7 +638,7 @@ void sat_sassasui() {
 // UNSIGNED-NEXT:    store i16 [[RESIZE1]], i16* @uf_sat, align 2
 // UNSIGNED-NEXT:    ret void
 //
-void sat_ufsufsufs() {
+void sat_ufsufsufs(void) {
   uf_sat = uf_sat / uf_sat;
 }
 
@@ -674,6 +674,6 @@ void sat_ufsufsufs() {
 // UNSIGNED-NEXT:    store i16 [[RESIZE2]], i16* @usa_sat, align 2
 // UNSIGNED-NEXT:    ret void
 //
-void sat_usasusasi() {
+void sat_usasusasi(void) {
   usa_sat = usa_sat / i;
 }
diff --git a/clang/test/Frontend/fixed_point_errors.c b/clang/test/Frontend/fixed_point_errors.c
index 6c41bf6df163..2d12a1ebb10b 100644
--- a/clang/test/Frontend/fixed_point_errors.c
+++ b/clang/test/Frontend/fixed_point_errors.c
@@ -149,7 +149,7 @@ _Accum dec_with_hex_exp2 = 0.1P10k;    // expected-error{{invalid suffix 'P10k'
 _Accum hex_with_dex_exp1 = 0x0.1e10k;  // expected-error{{hexadecimal floating constant requires an exponent}}
 _Accum hex_with_dex_exp2 = 0x0.1E10k;  // expected-error{{hexadecimal floating constant requires an exponent}}
 
-void CheckSuffixOnIntegerLiterals() {
+void CheckSuffixOnIntegerLiterals(void) {
   _Accum short_acc_int;
   _Accum acc_int;
   _Accum long_acc_int;
diff --git a/clang/test/Frontend/fixed_point_mul.c b/clang/test/Frontend/fixed_point_mul.c
index eeb80dd08d94..e4a6b8c83b06 100644
--- a/clang/test/Frontend/fixed_point_mul.c
+++ b/clang/test/Frontend/fixed_point_mul.c
@@ -36,7 +36,7 @@ _Bool b;
 // CHECK-NEXT:    store i16 [[TMP2]], i16* @sa, align 2
 // CHECK-NEXT:    ret void
 //
-void smul_sasasa() {
+void smul_sasasa(void) {
   sa = sa * sa;
 }
 
@@ -50,7 +50,7 @@ void smul_sasasa() {
 // CHECK-NEXT:    store i32 [[TMP2]], i32* @a, align 4
 // CHECK-NEXT:    ret void
 //
-void smul_asaa() {
+void smul_asaa(void) {
   a = sa * a;
 }
 
@@ -63,7 +63,7 @@ void smul_asaa() {
 // CHECK-NEXT:    store i16 [[TMP2]], i16* @sa, align 2
 // CHECK-NEXT:    ret void
 //
-void smul_sasasf() {
+void smul_sasasf(void) {
   sa = sa * sf;
 }
 
@@ -80,7 +80,7 @@ void smul_sasasf() {
 // CHECK-NEXT:    store i16 [[RESIZE2]], i16* @sa, align 2
 // CHECK-NEXT:    ret void
 //
-void smul_sasaf() {
+void smul_sasaf(void) {
   sa = sa * f;
 }
 
@@ -94,7 +94,7 @@ void smul_sasaf() {
 // CHECK-NEXT:    store i32 [[TMP2]], i32* @a, align 4
 // CHECK-NEXT:    ret void
 //
-void smul_aasf() {
+void smul_aasf(void) {
   a = a * sf;
 }
 
@@ -111,7 +111,7 @@ void smul_aasf() {
 // CHECK-NEXT:    store i32 [[RESIZE2]], i32* @a, align 4
 // CHECK-NEXT:    ret void
 //
-void smul_aalf() {
+void smul_aalf(void) {
   a = a * lf;
 }
 
@@ -136,7 +136,7 @@ void smul_aalf() {
 // UNSIGNED-NEXT:    store i16 [[TMP2]], i16* @sa, align 2
 // UNSIGNED-NEXT:    ret void
 //
-void smul_sasausa() {
+void smul_sasausa(void) {
   sa = sa * usa;
 }
 
@@ -163,7 +163,7 @@ void smul_sasausa() {
 // UNSIGNED-NEXT:    store i32 [[TMP2]], i32* @a, align 4
 // UNSIGNED-NEXT:    ret void
 //
-void smul_asaua() {
+void smul_asaua(void) {
   a = sa * ua;
 }
 
@@ -189,7 +189,7 @@ void smul_asaua() {
 // UNSIGNED-NEXT:    store i16 [[TMP2]], i16* @sa, align 2
 // UNSIGNED-NEXT:    ret void
 //
-void smul_sasausf() {
+void smul_sasausf(void) {
   sa = sa * usf;
 }
 
@@ -219,7 +219,7 @@ void smul_sasausf() {
 // UNSIGNED-NEXT:    store i16 [[RESIZE2]], i16* @sa, align 2
 // UNSIGNED-NEXT:    ret void
 //
-void smul_sasaulf() {
+void smul_sasaulf(void) {
   sa = sa * ulf;
 }
 
@@ -235,7 +235,7 @@ void smul_sasaulf() {
 // CHECK-NEXT:    store i32 [[TMP6]], i32* @a, align 4
 // CHECK-NEXT:    ret void
 //
-void smul_aaaaa() {
+void smul_aaaaa(void) {
   a = a * a2 * a3 * a4;
 }
 
@@ -256,7 +256,7 @@ void smul_aaaaa() {
 // UNSIGNED-NEXT:    store i16 [[TMP2]], i16* @usa, align 2
 // UNSIGNED-NEXT:    ret void
 //
-void umul_usausausa() {
+void umul_usausausa(void) {
   usa = usa * usa;
 }
 
@@ -280,7 +280,7 @@ void umul_usausausa() {
 // UNSIGNED-NEXT:    store i32 [[TMP2]], i32* @ua, align 4
 // UNSIGNED-NEXT:    ret void
 //
-void umul_uausaua() {
+void umul_uausaua(void) {
   ua = usa * ua;
 }
 
@@ -302,7 +302,7 @@ void umul_uausaua() {
 // UNSIGNED-NEXT:    store i16 [[TMP2]], i16* @usa, align 2
 // UNSIGNED-NEXT:    ret void
 //
-void umul_usausausf() {
+void umul_usausausf(void) {
   usa = usa * usf;
 }
 
@@ -332,7 +332,7 @@ void umul_usausausf() {
 // UNSIGNED-NEXT:    store i16 [[RESIZE2]], i16* @usa, align 2
 // UNSIGNED-NEXT:    ret void
 //
-void umul_usausauf() {
+void umul_usausauf(void) {
   usa = usa * uf;
 }
 
@@ -349,7 +349,7 @@ void umul_usausauf() {
 // CHECK-NEXT:    store i16 [[RESIZE2]], i16* @sa, align 2
 // CHECK-NEXT:    ret void
 //
-void int_sasai() {
+void int_sasai(void) {
   sa = sa * i;
 }
 
@@ -365,7 +365,7 @@ void int_sasai() {
 // CHECK-NEXT:    store i16 [[RESIZE2]], i16* @sa, align 2
 // CHECK-NEXT:    ret void
 //
-void int_sasaui() {
+void int_sasaui(void) {
   sa = sa * ui;
 }
 
@@ -393,7 +393,7 @@ void int_sasaui() {
 // UNSIGNED-NEXT:    store i16 [[RESIZE2]], i16* @usa, align 2
 // UNSIGNED-NEXT:    ret void
 //
-void int_usausai() {
+void int_usausai(void) {
   usa = usa * i;
 }
 
@@ -421,7 +421,7 @@ void int_usausai() {
 // UNSIGNED-NEXT:    store i16 [[RESIZE2]], i16* @usa, align 2
 // UNSIGNED-NEXT:    ret void
 //
-void int_usausaui() {
+void int_usausaui(void) {
   usa = usa * ui;
 }
 
@@ -437,7 +437,7 @@ void int_usausaui() {
 // CHECK-NEXT:    store i32 [[RESIZE2]], i32* @lf, align 4
 // CHECK-NEXT:    ret void
 //
-void int_lflfui() {
+void int_lflfui(void) {
   lf = lf * ui;
 }
 
@@ -455,7 +455,7 @@ void int_lflfui() {
 // CHECK-NEXT:    store i32 [[RESIZE2]], i32* @a, align 4
 // CHECK-NEXT:    ret void
 //
-void int_aab() {
+void int_aab(void) {
   a = a * b;
 }
 
@@ -471,7 +471,7 @@ void int_aab() {
 // CHECK-NEXT:    store i32 [[RESIZE2]], i32* @a, align 4
 // CHECK-NEXT:    ret void
 //
-void int_aia() {
+void int_aia(void) {
   a = i * a;
 }
 
@@ -499,7 +499,7 @@ void int_aia() {
 // UNSIGNED-NEXT:    store i16 [[RESIZE2]], i16* @usa, align 2
 // UNSIGNED-NEXT:    ret void
 //
-void int_usauiusa() {
+void int_usauiusa(void) {
   usa = ui * usa;
 }
 
@@ -515,7 +515,7 @@ void int_usauiusa() {
 // CHECK-NEXT:    store i16 [[RESIZE2]], i16* @sa, align 2
 // CHECK-NEXT:    ret void
 //
-void int_sauisa() {
+void int_sauisa(void) {
   sa = ui * sa;
 }
 
@@ -528,7 +528,7 @@ void int_sauisa() {
 // CHECK-NEXT:    store i16 [[TMP2]], i16* @sa_sat, align 2
 // CHECK-NEXT:    ret void
 //
-void sat_sassasas() {
+void sat_sassasas(void) {
   sa_sat = sa * sa_sat;
 }
 
@@ -550,7 +550,7 @@ void sat_sassasas() {
 // UNSIGNED-NEXT:    store i16 [[RESIZE1]], i16* @usa_sat, align 2
 // UNSIGNED-NEXT:    ret void
 //
-void sat_usasusausas() {
+void sat_usasusausas(void) {
   usa_sat = usa * usa_sat;
 }
 
@@ -576,7 +576,7 @@ void sat_usasusausas() {
 // UNSIGNED-NEXT:    store i32 [[RESIZE2]], i32* @ua_sat, align 4
 // UNSIGNED-NEXT:    ret void
 //
-void sat_uasuausas() {
+void sat_uasuausas(void) {
   ua_sat = ua * usa_sat;
 }
 
@@ -596,7 +596,7 @@ void sat_uasuausas() {
 // CHECK-NEXT:    store i16 [[RESIZE2]], i16* @sa_sat, align 2
 // CHECK-NEXT:    ret void
 //
-void sat_sassasi() {
+void sat_sassasi(void) {
   sa_sat = sa_sat * i;
 }
 
@@ -616,7 +616,7 @@ void sat_sassasi() {
 // CHECK-NEXT:    store i16 [[RESIZE2]], i16* @sa_sat, align 2
 // CHECK-NEXT:    ret void
 //
-void sat_sassasui() {
+void sat_sassasui(void) {
   sa_sat = sa_sat * ui;
 }
 
@@ -638,7 +638,7 @@ void sat_sassasui() {
 // UNSIGNED-NEXT:    store i16 [[RESIZE1]], i16* @uf_sat, align 2
 // UNSIGNED-NEXT:    ret void
 //
-void sat_ufsufsufs() {
+void sat_ufsufsufs(void) {
   uf_sat = uf_sat * uf_sat;
 }
 
@@ -674,6 +674,6 @@ void sat_ufsufsufs() {
 // UNSIGNED-NEXT:    store i16 [[RESIZE2]], i16* @usa_sat, align 2
 // UNSIGNED-NEXT:    ret void
 //
-void sat_usasusasi() {
+void sat_usasusasi(void) {
   usa_sat = usa_sat * i;
 }
diff --git a/clang/test/Frontend/fixed_point_same_fbits.c b/clang/test/Frontend/fixed_point_same_fbits.c
index 1d116b7dfa21..43c6392f4679 100644
--- a/clang/test/Frontend/fixed_point_same_fbits.c
+++ b/clang/test/Frontend/fixed_point_same_fbits.c
@@ -4,7 +4,7 @@
 /* The scale for unsigned fixed point types should be the same as that of signed
  * fixed point types when -fsame-fbits is enabled. */
 
-void func() {
+void func(void) {
   unsigned short _Accum u_short_accum = 0.5uhk;
   unsigned _Accum u_accum = 0.5uk;
   unsigned long _Accum u_long_accum = 0.5ulk;
diff --git a/clang/test/Frontend/fixed_point_shift.c b/clang/test/Frontend/fixed_point_shift.c
index a3d758798dfa..f334f028d69b 100644
--- a/clang/test/Frontend/fixed_point_shift.c
+++ b/clang/test/Frontend/fixed_point_shift.c
@@ -43,7 +43,7 @@ unsigned u;
 // CHECK-NEXT:    store i16 [[TMP3]], i16* @sa, align 2
 // CHECK-NEXT:    ret void
 //
-void sleft_sasai() {
+void sleft_sasai(void) {
   sa = sa << i;
 }
 
@@ -55,7 +55,7 @@ void sleft_sasai() {
 // CHECK-NEXT:    store i32 [[TMP2]], i32* @a, align 4
 // CHECK-NEXT:    ret void
 //
-void sleft_aai() {
+void sleft_aai(void) {
   a = a << i;
 }
 
@@ -68,7 +68,7 @@ void sleft_aai() {
 // CHECK-NEXT:    store i64 [[TMP3]], i64* @la, align 8
 // CHECK-NEXT:    ret void
 //
-void sleft_lalai() {
+void sleft_lalai(void) {
   la = la << i;
 }
 
@@ -81,7 +81,7 @@ void sleft_lalai() {
 // CHECK-NEXT:    store i8 [[TMP3]], i8* @sf, align 1
 // CHECK-NEXT:    ret void
 //
-void sleft_sfsfi() {
+void sleft_sfsfi(void) {
   sf = sf << i;
 }
 
@@ -94,7 +94,7 @@ void sleft_sfsfi() {
 // CHECK-NEXT:    store i16 [[TMP3]], i16* @f, align 2
 // CHECK-NEXT:    ret void
 //
-void sleft_ffi() {
+void sleft_ffi(void) {
   f = f << i;
 }
 
@@ -106,7 +106,7 @@ void sleft_ffi() {
 // CHECK-NEXT:    store i32 [[TMP2]], i32* @lf, align 4
 // CHECK-NEXT:    ret void
 //
-void sleft_lflfi() {
+void sleft_lflfi(void) {
   lf = lf << i;
 }
 
@@ -118,7 +118,7 @@ void sleft_lflfi() {
 // CHECK-NEXT:    store i32 [[TMP2]], i32* @a, align 4
 // CHECK-NEXT:    ret void
 //
-void sleft_aau() {
+void sleft_aau(void) {
   a = a << u;
 }
 
@@ -131,7 +131,7 @@ void sleft_aau() {
 // CHECK-NEXT:    store i16 [[TMP3]], i16* @f, align 2
 // CHECK-NEXT:    ret void
 //
-void sleft_ffu() {
+void sleft_ffu(void) {
   f = f << u;
 }
 
@@ -145,7 +145,7 @@ void sleft_ffu() {
 // CHECK-NEXT:    store i16 [[TMP3]], i16* @usa, align 2
 // CHECK-NEXT:    ret void
 //
-void uleft_usausai() {
+void uleft_usausai(void) {
   usa = usa << i;
 }
 
@@ -157,7 +157,7 @@ void uleft_usausai() {
 // CHECK-NEXT:    store i32 [[TMP2]], i32* @ua, align 4
 // CHECK-NEXT:    ret void
 //
-void uleft_uauai() {
+void uleft_uauai(void) {
   ua = ua << i;
 }
 
@@ -170,7 +170,7 @@ void uleft_uauai() {
 // CHECK-NEXT:    store i64 [[TMP3]], i64* @ula, align 8
 // CHECK-NEXT:    ret void
 //
-void uleft_ulaulai() {
+void uleft_ulaulai(void) {
   ula = ula << i;
 }
 
@@ -183,7 +183,7 @@ void uleft_ulaulai() {
 // CHECK-NEXT:    store i8 [[TMP3]], i8* @usf, align 1
 // CHECK-NEXT:    ret void
 //
-void uleft_usfusfi() {
+void uleft_usfusfi(void) {
   usf = usf << i;
 }
 
@@ -196,7 +196,7 @@ void uleft_usfusfi() {
 // CHECK-NEXT:    store i16 [[TMP3]], i16* @uf, align 2
 // CHECK-NEXT:    ret void
 //
-void uleft_ufufi() {
+void uleft_ufufi(void) {
   uf = uf << i;
 }
 
@@ -208,7 +208,7 @@ void uleft_ufufi() {
 // CHECK-NEXT:    store i32 [[TMP2]], i32* @ulf, align 4
 // CHECK-NEXT:    ret void
 //
-void uleft_ulfulfi() {
+void uleft_ulfulfi(void) {
   ulf = ulf << i;
 }
 
@@ -220,7 +220,7 @@ void uleft_ulfulfi() {
 // CHECK-NEXT:    store i32 [[TMP2]], i32* @ua, align 4
 // CHECK-NEXT:    ret void
 //
-void uleft_uauau() {
+void uleft_uauau(void) {
   ua = ua << u;
 }
 
@@ -233,7 +233,7 @@ void uleft_uauau() {
 // CHECK-NEXT:    store i16 [[TMP3]], i16* @uf, align 2
 // CHECK-NEXT:    ret void
 //
-void uleft_ufufu() {
+void uleft_ufufu(void) {
   uf = uf << u;
 }
 
@@ -247,7 +247,7 @@ void uleft_ufufu() {
 // CHECK-NEXT:    store i16 [[TMP3]], i16* @sa, align 2
 // CHECK-NEXT:    ret void
 //
-void sright_sasai() {
+void sright_sasai(void) {
   sa = sa >> i;
 }
 
@@ -259,7 +259,7 @@ void sright_sasai() {
 // CHECK-NEXT:    store i32 [[TMP2]], i32* @a, align 4
 // CHECK-NEXT:    ret void
 //
-void sright_aai() {
+void sright_aai(void) {
   a = a >> i;
 }
 
@@ -272,7 +272,7 @@ void sright_aai() {
 // CHECK-NEXT:    store i64 [[TMP3]], i64* @la, align 8
 // CHECK-NEXT:    ret void
 //
-void sright_lalai() {
+void sright_lalai(void) {
   la = la >> i;
 }
 
@@ -285,7 +285,7 @@ void sright_lalai() {
 // CHECK-NEXT:    store i8 [[TMP3]], i8* @sf, align 1
 // CHECK-NEXT:    ret void
 //
-void sright_sfsfi() {
+void sright_sfsfi(void) {
   sf = sf >> i;
 }
 
@@ -298,7 +298,7 @@ void sright_sfsfi() {
 // CHECK-NEXT:    store i16 [[TMP3]], i16* @f, align 2
 // CHECK-NEXT:    ret void
 //
-void sright_ffi() {
+void sright_ffi(void) {
   f = f >> i;
 }
 
@@ -310,7 +310,7 @@ void sright_ffi() {
 // CHECK-NEXT:    store i32 [[TMP2]], i32* @lf, align 4
 // CHECK-NEXT:    ret void
 //
-void sright_lflfi() {
+void sright_lflfi(void) {
   lf = lf >> i;
 }
 
@@ -322,7 +322,7 @@ void sright_lflfi() {
 // CHECK-NEXT:    store i32 [[TMP2]], i32* @a, align 4
 // CHECK-NEXT:    ret void
 //
-void sright_aau() {
+void sright_aau(void) {
   a = a >> u;
 }
 
@@ -335,7 +335,7 @@ void sright_aau() {
 // CHECK-NEXT:    store i16 [[TMP3]], i16* @f, align 2
 // CHECK-NEXT:    ret void
 //
-void sright_ffu() {
+void sright_ffu(void) {
   f = f >> u;
 }
 
@@ -349,7 +349,7 @@ void sright_ffu() {
 // CHECK-NEXT:    store i16 [[TMP3]], i16* @usa, align 2
 // CHECK-NEXT:    ret void
 //
-void uright_usausai() {
+void uright_usausai(void) {
   usa = usa >> i;
 }
 
@@ -361,7 +361,7 @@ void uright_usausai() {
 // CHECK-NEXT:    store i32 [[TMP2]], i32* @ua, align 4
 // CHECK-NEXT:    ret void
 //
-void uright_uauai() {
+void uright_uauai(void) {
   ua = ua >> i;
 }
 
@@ -374,7 +374,7 @@ void uright_uauai() {
 // CHECK-NEXT:    store i64 [[TMP3]], i64* @ula, align 8
 // CHECK-NEXT:    ret void
 //
-void uright_ulaulai() {
+void uright_ulaulai(void) {
   ula = ula >> i;
 }
 
@@ -387,7 +387,7 @@ void uright_ulaulai() {
 // CHECK-NEXT:    store i8 [[TMP3]], i8* @usf, align 1
 // CHECK-NEXT:    ret void
 //
-void uright_usfusfi() {
+void uright_usfusfi(void) {
   usf = usf >> i;
 }
 
@@ -400,7 +400,7 @@ void uright_usfusfi() {
 // CHECK-NEXT:    store i16 [[TMP3]], i16* @uf, align 2
 // CHECK-NEXT:    ret void
 //
-void uright_ufufi() {
+void uright_ufufi(void) {
   uf = uf >> i;
 }
 
@@ -412,7 +412,7 @@ void uright_ufufi() {
 // CHECK-NEXT:    store i32 [[TMP2]], i32* @ulf, align 4
 // CHECK-NEXT:    ret void
 //
-void uright_ulfulfi() {
+void uright_ulfulfi(void) {
   ulf = ulf >> i;
 }
 
@@ -424,7 +424,7 @@ void uright_ulfulfi() {
 // CHECK-NEXT:    store i32 [[TMP2]], i32* @ua, align 4
 // CHECK-NEXT:    ret void
 //
-void uright_uauau() {
+void uright_uauau(void) {
   ua = ua >> u;
 }
 
@@ -437,7 +437,7 @@ void uright_uauau() {
 // CHECK-NEXT:    store i16 [[TMP3]], i16* @uf, align 2
 // CHECK-NEXT:    ret void
 //
-void uright_ufufu() {
+void uright_ufufu(void) {
   uf = uf >> u;
 }
 
@@ -451,7 +451,7 @@ void uright_ufufu() {
 // CHECK-NEXT:    store i16 [[TMP3]], i16* @sa_sat, align 2
 // CHECK-NEXT:    ret void
 //
-void satleft_sassasi() {
+void satleft_sassasi(void) {
   sa_sat = sa_sat << i;
 }
 
@@ -463,7 +463,7 @@ void satleft_sassasi() {
 // CHECK-NEXT:    store i32 [[TMP2]], i32* @a_sat, align 4
 // CHECK-NEXT:    ret void
 //
-void satleft_asasi() {
+void satleft_asasi(void) {
   a_sat = a_sat << i;
 }
 
@@ -476,7 +476,7 @@ void satleft_asasi() {
 // CHECK-NEXT:    store i8 [[TMP3]], i8* @sf_sat, align 1
 // CHECK-NEXT:    ret void
 //
-void satleft_sfssfsi() {
+void satleft_sfssfsi(void) {
   sf_sat = sf_sat << i;
 }
 
@@ -489,7 +489,7 @@ void satleft_sfssfsi() {
 // CHECK-NEXT:    store i16 [[TMP3]], i16* @f_sat, align 2
 // CHECK-NEXT:    ret void
 //
-void satleft_fsfsi() {
+void satleft_fsfsi(void) {
   f_sat = f_sat << i;
 }
 
@@ -511,7 +511,7 @@ void satleft_fsfsi() {
 // UNSIGNED-NEXT:    store i16 [[TMP3]], i16* @usa_sat, align 2
 // UNSIGNED-NEXT:    ret void
 //
-void satleft_usasusasi() {
+void satleft_usasusasi(void) {
   usa_sat = usa_sat << i;
 }
 
@@ -531,7 +531,7 @@ void satleft_usasusasi() {
 // UNSIGNED-NEXT:    store i32 [[TMP2]], i32* @ua_sat, align 4
 // UNSIGNED-NEXT:    ret void
 //
-void satleft_uasuasi() {
+void satleft_uasuasi(void) {
   ua_sat = ua_sat << i;
 }
 
@@ -553,7 +553,7 @@ void satleft_uasuasi() {
 // UNSIGNED-NEXT:    store i8 [[TMP3]], i8* @usf_sat, align 1
 // UNSIGNED-NEXT:    ret void
 //
-void satleft_usfsusfsi() {
+void satleft_usfsusfsi(void) {
   usf_sat = usf_sat << i;
 }
 
@@ -575,6 +575,6 @@ void satleft_usfsusfsi() {
 // UNSIGNED-NEXT:    store i16 [[TMP3]], i16* @uf_sat, align 2
 // UNSIGNED-NEXT:    ret void
 //
-void satleft_ufsufsi() {
+void satleft_ufsufsi(void) {
   uf_sat = uf_sat << i;
 }
diff --git a/clang/test/Frontend/fixed_point_sub.c b/clang/test/Frontend/fixed_point_sub.c
index 6446d76fbaa5..e321a60cd67b 100644
--- a/clang/test/Frontend/fixed_point_sub.c
+++ b/clang/test/Frontend/fixed_point_sub.c
@@ -36,7 +36,7 @@ _Bool b;
 // CHECK-NEXT:    store i16 [[TMP2]], i16* @sa, align 2
 // CHECK-NEXT:    ret void
 //
-void ssub_sasasa() {
+void ssub_sasasa(void) {
   sa = sa - sa;
 }
 
@@ -50,7 +50,7 @@ void ssub_sasasa() {
 // CHECK-NEXT:    store i32 [[TMP2]], i32* @a, align 4
 // CHECK-NEXT:    ret void
 //
-void ssub_asaa() {
+void ssub_asaa(void) {
   a = sa - a;
 }
 
@@ -63,7 +63,7 @@ void ssub_asaa() {
 // CHECK-NEXT:    store i16 [[TMP2]], i16* @sa, align 2
 // CHECK-NEXT:    ret void
 //
-void ssub_sasasf() {
+void ssub_sasasf(void) {
   sa = sa - sf;
 }
 
@@ -80,7 +80,7 @@ void ssub_sasasf() {
 // CHECK-NEXT:    store i16 [[RESIZE2]], i16* @sa, align 2
 // CHECK-NEXT:    ret void
 //
-void ssub_sasaf() {
+void ssub_sasaf(void) {
   sa = sa - f;
 }
 
@@ -94,7 +94,7 @@ void ssub_sasaf() {
 // CHECK-NEXT:    store i32 [[TMP2]], i32* @a, align 4
 // CHECK-NEXT:    ret void
 //
-void ssub_aasf() {
+void ssub_aasf(void) {
   a = a - sf;
 }
 
@@ -111,7 +111,7 @@ void ssub_aasf() {
 // CHECK-NEXT:    store i32 [[RESIZE2]], i32* @a, align 4
 // CHECK-NEXT:    ret void
 //
-void ssub_aalf() {
+void ssub_aalf(void) {
   a = a - lf;
 }
 
@@ -136,7 +136,7 @@ void ssub_aalf() {
 // UNSIGNED-NEXT:    store i16 [[TMP2]], i16* @sa, align 2
 // UNSIGNED-NEXT:    ret void
 //
-void ssub_sasausa() {
+void ssub_sasausa(void) {
   sa = sa - usa;
 }
 
@@ -163,7 +163,7 @@ void ssub_sasausa() {
 // UNSIGNED-NEXT:    store i32 [[TMP2]], i32* @a, align 4
 // UNSIGNED-NEXT:    ret void
 //
-void ssub_asaua() {
+void ssub_asaua(void) {
   a = sa - ua;
 }
 
@@ -189,7 +189,7 @@ void ssub_asaua() {
 // UNSIGNED-NEXT:    store i16 [[TMP2]], i16* @sa, align 2
 // UNSIGNED-NEXT:    ret void
 //
-void ssub_sasausf() {
+void ssub_sasausf(void) {
   sa = sa - usf;
 }
 
@@ -219,7 +219,7 @@ void ssub_sasausf() {
 // UNSIGNED-NEXT:    store i16 [[RESIZE2]], i16* @sa, align 2
 // UNSIGNED-NEXT:    ret void
 //
-void ssub_sasaulf() {
+void ssub_sasaulf(void) {
   sa = sa - ulf;
 }
 
@@ -235,7 +235,7 @@ void ssub_sasaulf() {
 // CHECK-NEXT:    store i32 [[TMP6]], i32* @a, align 4
 // CHECK-NEXT:    ret void
 //
-void ssub_aaaaa() {
+void ssub_aaaaa(void) {
   a = a - a2 - a3 - a4;
 }
 
@@ -248,7 +248,7 @@ void ssub_aaaaa() {
 // CHECK-NEXT:    store i16 [[TMP2]], i16* @usa, align 2
 // CHECK-NEXT:    ret void
 //
-void usub_usausausa() {
+void usub_usausausa(void) {
   usa = usa - usa;
 }
 
@@ -262,7 +262,7 @@ void usub_usausausa() {
 // CHECK-NEXT:    store i32 [[TMP2]], i32* @ua, align 4
 // CHECK-NEXT:    ret void
 //
-void usub_uausaua() {
+void usub_uausaua(void) {
   ua = usa - ua;
 }
 
@@ -275,7 +275,7 @@ void usub_uausaua() {
 // CHECK-NEXT:    store i16 [[TMP2]], i16* @usa, align 2
 // CHECK-NEXT:    ret void
 //
-void usub_usausausf() {
+void usub_usausausf(void) {
   usa = usa - usf;
 }
 
@@ -292,7 +292,7 @@ void usub_usausausf() {
 // CHECK-NEXT:    store i16 [[RESIZE2]], i16* @usa, align 2
 // CHECK-NEXT:    ret void
 //
-void usub_usausauf() {
+void usub_usausauf(void) {
   usa = usa - uf;
 }
 
@@ -309,7 +309,7 @@ void usub_usausauf() {
 // CHECK-NEXT:    store i16 [[RESIZE2]], i16* @sa, align 2
 // CHECK-NEXT:    ret void
 //
-void int_sasai() {
+void int_sasai(void) {
   sa = sa - i;
 }
 
@@ -325,7 +325,7 @@ void int_sasai() {
 // CHECK-NEXT:    store i16 [[RESIZE2]], i16* @sa, align 2
 // CHECK-NEXT:    ret void
 //
-void int_sasaui() {
+void int_sasaui(void) {
   sa = sa - ui;
 }
 
@@ -353,7 +353,7 @@ void int_sasaui() {
 // UNSIGNED-NEXT:    store i16 [[RESIZE2]], i16* @usa, align 2
 // UNSIGNED-NEXT:    ret void
 //
-void int_usausai() {
+void int_usausai(void) {
   usa = usa - i;
 }
 
@@ -381,7 +381,7 @@ void int_usausai() {
 // UNSIGNED-NEXT:    store i16 [[RESIZE2]], i16* @usa, align 2
 // UNSIGNED-NEXT:    ret void
 //
-void int_usausaui() {
+void int_usausaui(void) {
   usa = usa - ui;
 }
 
@@ -397,7 +397,7 @@ void int_usausaui() {
 // CHECK-NEXT:    store i32 [[RESIZE2]], i32* @lf, align 4
 // CHECK-NEXT:    ret void
 //
-void int_lflfui() {
+void int_lflfui(void) {
   lf = lf - ui;
 }
 
@@ -415,7 +415,7 @@ void int_lflfui() {
 // CHECK-NEXT:    store i32 [[RESIZE2]], i32* @a, align 4
 // CHECK-NEXT:    ret void
 //
-void int_aab() {
+void int_aab(void) {
   a = a - b;
 }
 
@@ -428,7 +428,7 @@ void int_aab() {
 // CHECK-NEXT:    store i16 [[TMP2]], i16* @sa_sat, align 2
 // CHECK-NEXT:    ret void
 //
-void sat_sassasas() {
+void sat_sassasas(void) {
   sa_sat = sa - sa_sat;
 }
 
@@ -452,7 +452,7 @@ void sat_sassasas() {
 // UNSIGNED-NEXT:    store i16 [[RESIZE1]], i16* @usa_sat, align 2
 // UNSIGNED-NEXT:    ret void
 //
-void sat_usasusausas() {
+void sat_usasusausas(void) {
   usa_sat = usa - usa_sat;
 }
 
@@ -480,7 +480,7 @@ void sat_usasusausas() {
 // UNSIGNED-NEXT:    store i32 [[RESIZE2]], i32* @ua_sat, align 4
 // UNSIGNED-NEXT:    ret void
 //
-void sat_uasuausas() {
+void sat_uasuausas(void) {
   ua_sat = ua - usa_sat;
 }
 
@@ -500,7 +500,7 @@ void sat_uasuausas() {
 // CHECK-NEXT:    store i16 [[RESIZE2]], i16* @sa_sat, align 2
 // CHECK-NEXT:    ret void
 //
-void sat_sassasi() {
+void sat_sassasi(void) {
   sa_sat = sa_sat - i;
 }
 
@@ -520,7 +520,7 @@ void sat_sassasi() {
 // CHECK-NEXT:    store i16 [[RESIZE2]], i16* @sa_sat, align 2
 // CHECK-NEXT:    ret void
 //
-void sat_sassasui() {
+void sat_sassasui(void) {
   sa_sat = sa_sat - ui;
 }
 
@@ -544,7 +544,7 @@ void sat_sassasui() {
 // UNSIGNED-NEXT:    store i16 [[RESIZE1]], i16* @uf_sat, align 2
 // UNSIGNED-NEXT:    ret void
 //
-void sat_ufsufsufs() {
+void sat_ufsufsufs(void) {
   uf_sat = uf_sat - uf_sat;
 }
 
@@ -580,6 +580,6 @@ void sat_ufsufsufs() {
 // UNSIGNED-NEXT:    store i16 [[RESIZE2]], i16* @usa_sat, align 2
 // UNSIGNED-NEXT:    ret void
 //
-void sat_usasusasi() {
+void sat_usasusasi(void) {
   usa_sat = usa_sat - i;
 }
diff --git a/clang/test/Frontend/fixed_point_to_bool.c b/clang/test/Frontend/fixed_point_to_bool.c
index 13b39b8e7ac4..20482b8c9d85 100644
--- a/clang/test/Frontend/fixed_point_to_bool.c
+++ b/clang/test/Frontend/fixed_point_to_bool.c
@@ -4,7 +4,7 @@
 _Bool global_b = 1.0k;  // @global_b = {{*.}}global i8 1, align 1
 _Bool global_b2 = 0.0k; // @global_b2 = {{*.}}global i8 0, align 1
 
-void func() {
+void func(void) {
   _Accum a = 0.5k;
   unsigned _Accum ua = 0.5uk;
   _Bool b;
diff --git a/clang/test/Frontend/fixed_point_unary.c b/clang/test/Frontend/fixed_point_unary.c
index 6ce760daba11..90595040b52f 100644
--- a/clang/test/Frontend/fixed_point_unary.c
+++ b/clang/test/Frontend/fixed_point_unary.c
@@ -25,7 +25,7 @@ int i;
 // CHECK-NEXT:    store i32 [[TMP1]], i32* @a, align 4
 // CHECK-NEXT:    ret void
 //
-void inc_a() {
+void inc_a(void) {
   a++;
 }
 
@@ -36,7 +36,7 @@ void inc_a() {
 // CHECK-NEXT:    store i16 [[TMP1]], i16* @f, align 2
 // CHECK-NEXT:    ret void
 //
-void inc_f() {
+void inc_f(void) {
   f++;
 }
 
@@ -47,7 +47,7 @@ void inc_f() {
 // CHECK-NEXT:    store i32 [[TMP1]], i32* @lf, align 4
 // CHECK-NEXT:    ret void
 //
-void inc_lf() {
+void inc_lf(void) {
   lf++;
 }
 
@@ -65,7 +65,7 @@ void inc_lf() {
 // UNSIGNED-NEXT:    store i32 [[TMP1]], i32* @ua, align 4
 // UNSIGNED-NEXT:    ret void
 //
-void inc_ua() {
+void inc_ua(void) {
   ua++;
 }
 
@@ -83,7 +83,7 @@ void inc_ua() {
 // UNSIGNED-NEXT:    store i16 [[TMP1]], i16* @usa, align 2
 // UNSIGNED-NEXT:    ret void
 //
-void inc_usa() {
+void inc_usa(void) {
   usa++;
 }
 
@@ -101,7 +101,7 @@ void inc_usa() {
 // UNSIGNED-NEXT:    store i16 [[TMP1]], i16* @uf, align 2
 // UNSIGNED-NEXT:    ret void
 //
-void inc_uf() {
+void inc_uf(void) {
   uf++;
 }
 
@@ -112,7 +112,7 @@ void inc_uf() {
 // CHECK-NEXT:    store i32 [[TMP1]], i32* @sa, align 4
 // CHECK-NEXT:    ret void
 //
-void inc_sa() {
+void inc_sa(void) {
   sa++;
 }
 
@@ -123,7 +123,7 @@ void inc_sa() {
 // CHECK-NEXT:    store i16 [[TMP1]], i16* @sf, align 2
 // CHECK-NEXT:    ret void
 //
-void inc_sf() {
+void inc_sf(void) {
   sf++;
 }
 
@@ -134,7 +134,7 @@ void inc_sf() {
 // CHECK-NEXT:    store i32 [[TMP1]], i32* @slf, align 4
 // CHECK-NEXT:    ret void
 //
-void inc_slf() {
+void inc_slf(void) {
   slf++;
 }
 
@@ -154,7 +154,7 @@ void inc_slf() {
 // UNSIGNED-NEXT:    store i32 [[RESIZE1]], i32* @sua, align 4
 // UNSIGNED-NEXT:    ret void
 //
-void inc_sua() {
+void inc_sua(void) {
   sua++;
 }
 
@@ -174,7 +174,7 @@ void inc_sua() {
 // UNSIGNED-NEXT:    store i16 [[RESIZE1]], i16* @susa, align 2
 // UNSIGNED-NEXT:    ret void
 //
-void inc_susa() {
+void inc_susa(void) {
   susa++;
 }
 
@@ -194,7 +194,7 @@ void inc_susa() {
 // UNSIGNED-NEXT:    store i16 [[RESIZE1]], i16* @suf, align 2
 // UNSIGNED-NEXT:    ret void
 //
-void inc_suf() {
+void inc_suf(void) {
   suf++;
 }
 
@@ -206,7 +206,7 @@ void inc_suf() {
 // CHECK-NEXT:    store i32 [[TMP1]], i32* @a, align 4
 // CHECK-NEXT:    ret void
 //
-void dec_a() {
+void dec_a(void) {
   a--;
 }
 
@@ -217,7 +217,7 @@ void dec_a() {
 // CHECK-NEXT:    store i16 [[TMP1]], i16* @f, align 2
 // CHECK-NEXT:    ret void
 //
-void dec_f() {
+void dec_f(void) {
   f--;
 }
 
@@ -228,7 +228,7 @@ void dec_f() {
 // CHECK-NEXT:    store i32 [[TMP1]], i32* @lf, align 4
 // CHECK-NEXT:    ret void
 //
-void dec_lf() {
+void dec_lf(void) {
   lf--;
 }
 
@@ -246,7 +246,7 @@ void dec_lf() {
 // UNSIGNED-NEXT:    store i32 [[TMP1]], i32* @ua, align 4
 // UNSIGNED-NEXT:    ret void
 //
-void dec_ua() {
+void dec_ua(void) {
   ua--;
 }
 
@@ -264,7 +264,7 @@ void dec_ua() {
 // UNSIGNED-NEXT:    store i16 [[TMP1]], i16* @usa, align 2
 // UNSIGNED-NEXT:    ret void
 //
-void dec_usa() {
+void dec_usa(void) {
   usa--;
 }
 
@@ -282,7 +282,7 @@ void dec_usa() {
 // UNSIGNED-NEXT:    store i16 [[TMP1]], i16* @uf, align 2
 // UNSIGNED-NEXT:    ret void
 //
-void dec_uf() {
+void dec_uf(void) {
   uf--;
 }
 
@@ -293,7 +293,7 @@ void dec_uf() {
 // CHECK-NEXT:    store i32 [[TMP1]], i32* @sa, align 4
 // CHECK-NEXT:    ret void
 //
-void dec_sa() {
+void dec_sa(void) {
   sa--;
 }
 
@@ -304,7 +304,7 @@ void dec_sa() {
 // CHECK-NEXT:    store i16 [[TMP1]], i16* @sf, align 2
 // CHECK-NEXT:    ret void
 //
-void dec_sf() {
+void dec_sf(void) {
   sf--;
 }
 
@@ -315,7 +315,7 @@ void dec_sf() {
 // CHECK-NEXT:    store i32 [[TMP1]], i32* @slf, align 4
 // CHECK-NEXT:    ret void
 //
-void dec_slf() {
+void dec_slf(void) {
   slf--;
 }
 
@@ -337,7 +337,7 @@ void dec_slf() {
 // UNSIGNED-NEXT:    store i32 [[RESIZE1]], i32* @sua, align 4
 // UNSIGNED-NEXT:    ret void
 //
-void dec_sua() {
+void dec_sua(void) {
   sua--;
 }
 
@@ -359,7 +359,7 @@ void dec_sua() {
 // UNSIGNED-NEXT:    store i16 [[RESIZE1]], i16* @susa, align 2
 // UNSIGNED-NEXT:    ret void
 //
-void dec_susa() {
+void dec_susa(void) {
   susa--;
 }
 
@@ -381,7 +381,7 @@ void dec_susa() {
 // UNSIGNED-NEXT:    store i16 [[RESIZE1]], i16* @suf, align 2
 // UNSIGNED-NEXT:    ret void
 //
-void dec_suf() {
+void dec_suf(void) {
   suf--;
 }
 
@@ -393,7 +393,7 @@ void dec_suf() {
 // CHECK-NEXT:    store i32 [[TMP1]], i32* @a, align 4
 // CHECK-NEXT:    ret void
 //
-void neg_a() {
+void neg_a(void) {
   a = -a;
 }
 
@@ -404,7 +404,7 @@ void neg_a() {
 // CHECK-NEXT:    store i16 [[TMP1]], i16* @f, align 2
 // CHECK-NEXT:    ret void
 //
-void neg_f() {
+void neg_f(void) {
   f = -f;
 }
 
@@ -415,7 +415,7 @@ void neg_f() {
 // CHECK-NEXT:    store i16 [[TMP1]], i16* @usa, align 2
 // CHECK-NEXT:    ret void
 //
-void neg_usa() {
+void neg_usa(void) {
   usa = -usa;
 }
 
@@ -426,7 +426,7 @@ void neg_usa() {
 // CHECK-NEXT:    store i16 [[TMP1]], i16* @uf, align 2
 // CHECK-NEXT:    ret void
 //
-void neg_uf() {
+void neg_uf(void) {
   uf = -uf;
 }
 
@@ -437,7 +437,7 @@ void neg_uf() {
 // CHECK-NEXT:    store i32 [[TMP1]], i32* @sa, align 4
 // CHECK-NEXT:    ret void
 //
-void neg_sa() {
+void neg_sa(void) {
   sa = -sa;
 }
 
@@ -448,7 +448,7 @@ void neg_sa() {
 // CHECK-NEXT:    store i16 [[TMP1]], i16* @sf, align 2
 // CHECK-NEXT:    ret void
 //
-void neg_sf() {
+void neg_sf(void) {
   sf = -sf;
 }
 
@@ -470,7 +470,7 @@ void neg_sf() {
 // UNSIGNED-NEXT:    store i16 [[RESIZE1]], i16* @susa, align 2
 // UNSIGNED-NEXT:    ret void
 //
-void neg_susa() {
+void neg_susa(void) {
   susa = -susa;
 }
 
@@ -492,7 +492,7 @@ void neg_susa() {
 // UNSIGNED-NEXT:    store i16 [[RESIZE1]], i16* @suf, align 2
 // UNSIGNED-NEXT:    ret void
 //
-void neg_suf() {
+void neg_suf(void) {
   suf = -suf;
 }
 
@@ -503,7 +503,7 @@ void neg_suf() {
 // CHECK-NEXT:    store i32 [[TMP0]], i32* @a, align 4
 // CHECK-NEXT:    ret void
 //
-void plus_a() {
+void plus_a(void) {
   a = +a;
 }
 
@@ -513,7 +513,7 @@ void plus_a() {
 // CHECK-NEXT:    store i16 [[TMP0]], i16* @uf, align 2
 // CHECK-NEXT:    ret void
 //
-void plus_uf() {
+void plus_uf(void) {
   uf = +uf;
 }
 
@@ -523,7 +523,7 @@ void plus_uf() {
 // CHECK-NEXT:    store i32 [[TMP0]], i32* @sa, align 4
 // CHECK-NEXT:    ret void
 //
-void plus_sa() {
+void plus_sa(void) {
   sa = +sa;
 }
 
@@ -537,7 +537,7 @@ void plus_sa() {
 // CHECK-NEXT:    store i32 [[LNOT_EXT]], i32* @i, align 4
 // CHECK-NEXT:    ret void
 //
-void not_a() {
+void not_a(void) {
   i = !a;
 }
 
@@ -550,7 +550,7 @@ void not_a() {
 // CHECK-NEXT:    store i32 [[LNOT_EXT]], i32* @i, align 4
 // CHECK-NEXT:    ret void
 //
-void not_uf() {
+void not_uf(void) {
   i = !uf;
 }
 
@@ -563,6 +563,6 @@ void not_uf() {
 // CHECK-NEXT:    store i32 [[LNOT_EXT]], i32* @i, align 4
 // CHECK-NEXT:    ret void
 //
-void not_susa() {
+void not_susa(void) {
   i = !susa;
 }
diff --git a/clang/test/Frontend/fixed_point_unknown_conversions.c b/clang/test/Frontend/fixed_point_unknown_conversions.c
index 8595901f9e9c..b80c571307cc 100644
--- a/clang/test/Frontend/fixed_point_unknown_conversions.c
+++ b/clang/test/Frontend/fixed_point_unknown_conversions.c
@@ -1,6 +1,6 @@
 // RUN: %clang_cc1 -verify -ffixed-point %s
 
-void func() {
+void func(void) {
   _Bool b;
   char c;
   int i;
diff --git a/clang/test/Frontend/ir-support.c b/clang/test/Frontend/ir-support.c
index f69161e8705c..d0c7dfa418ca 100644
--- a/clang/test/Frontend/ir-support.c
+++ b/clang/test/Frontend/ir-support.c
@@ -16,4 +16,4 @@
 // RUN: %clang_cc1 -S -o - %t.ll | grep -v '\.file' > %t.ll.s
 // RUN: diff %t.s %t.ll.s
 
-int f() { return 0; }
+int f(void) { return 0; }
diff --git a/clang/test/Frontend/noderef.c b/clang/test/Frontend/noderef.c
index d136ff0c7192..6b9a14316817 100644
--- a/clang/test/Frontend/noderef.c
+++ b/clang/test/Frontend/noderef.c
@@ -23,7 +23,7 @@ int NODEREF *func(int NODEREF *arg) {  // expected-note{{arg declared here}}
 
 void func2(int x) {}
 
-int test() {
+int test(void) {
   int NODEREF *p; // expected-note 34 {{p declared here}}
   int *p2;
 
diff --git a/clang/test/Frontend/noderef_on_non_pointers.m b/clang/test/Frontend/noderef_on_non_pointers.m
index ced7627bb5e8..de2f9dbde489 100644
--- a/clang/test/Frontend/noderef_on_non_pointers.m
+++ b/clang/test/Frontend/noderef_on_non_pointers.m
@@ -6,6 +6,6 @@
 + (id)new;
 @end
 
-void func() {
+void func(void) {
   id NODEREF obj = [NSObject new]; // expected-warning{{'noderef' can only be used on an array or pointer type}}
 }
diff --git a/clang/test/Frontend/stdin-input.c b/clang/test/Frontend/stdin-input.c
index 7b15482b8c51..e8c890efa09e 100644
--- a/clang/test/Frontend/stdin-input.c
+++ b/clang/test/Frontend/stdin-input.c
@@ -4,4 +4,4 @@
 // CHECK: source_filename = "test/foo.c"
 // CHECK: !DIFile(filename: "test/foo.c"
 
-int main() {}
+int main(void) {}
diff --git a/clang/test/Frontend/system-header-line-directive-ms-lineendings.c b/clang/test/Frontend/system-header-line-directive-ms-lineendings.c
index 57b7a27ea49c..92fc07f65e0d 100644
--- a/clang/test/Frontend/system-header-line-directive-ms-lineendings.c
+++ b/clang/test/Frontend/system-header-line-directive-ms-lineendings.c
@@ -9,12 +9,12 @@
 
 // CHECK: # 1 "{{.*}}system-header-line-directive-ms-lineendings.c" 2
 // CHECK: # 1 "{{.*}}noline.h" 1 3
-// CHECK: foo();
+// CHECK: foo(void);
 // CHECK: # 3 "{{.*}}system-header-line-directive-ms-lineendings.c" 2
 // CHECK: # 1 "{{.*}}line-directive-in-system.h" 1 3
 //      The "3" below indicates that "foo.h" is considered a system header.
 // CHECK: # 1 "foo.h" 3
-// CHECK: foo();
+// CHECK: foo(void);
 // CHECK: # 4 "{{.*}}system-header-line-directive-ms-lineendings.c" 2
 // CHECK: # 1 "{{.*}}line-directive.h" 1
 // CHECK: # 10 "foo.h"{{$}}
diff --git a/clang/test/Frontend/system-header-line-directive.c b/clang/test/Frontend/system-header-line-directive.c
index 9d4f09885f94..0de69196d76e 100644
--- a/clang/test/Frontend/system-header-line-directive.c
+++ b/clang/test/Frontend/system-header-line-directive.c
@@ -12,12 +12,12 @@
 
 // CHECK: # {{[0-9]+}} "{{.*}}system-header-line-directive.c" 2
 // CHECK: # 1 "{{.*}}noline.h" 1 3
-// CHECK: foo();
+// CHECK: foo(void);
 // CHECK: # 4 "{{.*}}system-header-line-directive.c" 2
 // CHECK: # 1 "{{.*}}line-directive-in-system.h" 1 3
 //      The "3" below indicates that "foo.h" is considered a system header.
 // CHECK: # 1 "foo.h" 3
-// CHECK: foo();
+// CHECK: foo(void);
 // CHECK: # {{[0-9]+}} "{{.*}}system-header-line-directive.c" 2
 // CHECK: # 1 "{{.*}}line-directive.h" 1
 // CHECK: # 10 "foo.h"{{$}}
diff --git a/clang/test/Frontend/verify-prefixes.c b/clang/test/Frontend/verify-prefixes.c
index c5b545cf84c0..38c2e57f75c3 100644
--- a/clang/test/Frontend/verify-prefixes.c
+++ b/clang/test/Frontend/verify-prefixes.c
@@ -100,7 +100,7 @@ GCONST int glb = 5;
 # define SCONST
 #endif
 
-void foo() {
+void foo(void) {
   LCONST int loc = 5;
   SCONST static int sta = 5;
   // We don't actually expect 1-2 occurrences of this error.  We're just
diff --git a/clang/test/Frontend/warning-mapping-2.c b/clang/test/Frontend/warning-mapping-2.c
index 4f7f1ee7606e..d2a2a21f1711 100644
--- a/clang/test/Frontend/warning-mapping-2.c
+++ b/clang/test/Frontend/warning-mapping-2.c
@@ -4,4 +4,4 @@
 // Expect *not* to see a diagnostic for "implicit declaration of function"
 // expected-no-diagnostics
 
-void f0() { f1(); }
+void f0(void) { f1(); }
diff --git a/clang/test/Headers/altivec-intrin.c b/clang/test/Headers/altivec-intrin.c
index c71b48da040d..50b85c0de308 100644
--- a/clang/test/Headers/altivec-intrin.c
+++ b/clang/test/Headers/altivec-intrin.c
@@ -7,7 +7,7 @@
 
 __attribute__((__aligned__(16))) float x[20];
 
-int main()
+int main(void)
 {
   vector unsigned char l = vec_lvsl (0, &x[1]); // expected-warning {{is deprecated: use assignment for unaligned little endian loads/stores}}
   vector unsigned char r = vec_lvsr (0, &x[1]); // expected-warning {{is deprecated: use assignment for unaligned little endian loads/stores}}
diff --git a/clang/test/Headers/arm-acle-header.c b/clang/test/Headers/arm-acle-header.c
index e50a68c64b0f..1084a8cf87e1 100644
--- a/clang/test/Headers/arm-acle-header.c
+++ b/clang/test/Headers/arm-acle-header.c
@@ -13,4 +13,4 @@
 #ifdef _MSC_VER
 #include <intrin.h>
 #endif
-void f() { __nop(); __dmb(0); __wfi(); }
+void f(void) { __nop(); __dmb(0); __wfi(); }
diff --git a/clang/test/Headers/c11.c b/clang/test/Headers/c11.c
index 6594823c2733..b5896316a82d 100644
--- a/clang/test/Headers/c11.c
+++ b/clang/test/Headers/c11.c
@@ -4,16 +4,16 @@
 // RUN: %clang_cc1 -fsyntax-only -verify -std=c11 -ffreestanding %s
 // RUN: %clang_cc1 -fsyntax-only -verify -std=c11 -triple i686-pc-win32 -fms-compatibility-version=17.00 %s
 
-noreturn int f(); // expected-error 1+{{}}
+noreturn int f(void); // expected-error 1+{{}}
 
 #include <stdnoreturn.h>
 #include <stdnoreturn.h>
 #include <stdnoreturn.h>
 
-int g();
-noreturn int g();
-int noreturn g();
-int g();
+int g(void);
+noreturn int g(void);
+int noreturn g(void);
+int g(void);
 
 #include <stdalign.h>
 _Static_assert(__alignas_is_defined, "");
diff --git a/clang/test/Headers/typedef_guards.c b/clang/test/Headers/typedef_guards.c
index 968b26d8c731..e934250f3707 100644
--- a/clang/test/Headers/typedef_guards.c
+++ b/clang/test/Headers/typedef_guards.c
@@ -22,8 +22,8 @@ typedef __typeof__(*L"") wchar_t;
 
 extern void foo(wchar_t x);
 extern void bar(size_t x);
-void *baz() { return NULL; }
-void quz() {
+void *baz(void) { return NULL; }
+void quz(void) {
   va_list y;
 }
 
diff --git a/clang/test/Headers/x86-header-warnings.c b/clang/test/Headers/x86-header-warnings.c
index 3306b95c1b48..35c457439c9f 100644
--- a/clang/test/Headers/x86-header-warnings.c
+++ b/clang/test/Headers/x86-header-warnings.c
@@ -7,7 +7,7 @@
 
 #include <x86intrin.h>
 
-void test0() {
+void test0(void) {
   // expected-no-diagnostics
   _MM_SET_DENORMALS_ZERO_MODE(_MM_DENORMALS_ZERO_ON);
   _MM_SET_DENORMALS_ZERO_MODE(_MM_DENORMALS_ZERO_OFF);
diff --git a/clang/test/Index/Core/index-pch.c b/clang/test/Index/Core/index-pch.c
index 773cfc59077e..f5f53466e039 100644
--- a/clang/test/Index/Core/index-pch.c
+++ b/clang/test/Index/Core/index-pch.c
@@ -3,10 +3,10 @@
 // RUN: c-index-test core -print-source-symbols -module-file %t.pch | FileCheck %s
 
 // CHECK: [[@LINE+1]]:6 | function/C | test1 | [[TEST1_USR:.*]] | [[TEST1_CG:.*]] | Decl | rel: 0
-void test1();
+void test1(void);
 
 // CHECK: [[@LINE+1]]:20 | function/C | test2 | [[TEST2_USR:.*]] | {{.*}} | Def | rel: 0
-static inline void test2() {
+static inline void test2(void) {
   // CHECK: [[@LINE+2]]:3 | function/C | test1 | [[TEST1_USR]] | [[TEST1_CG]] | Ref,Call,RelCall,RelCont | rel: 1
   // CHECK-NEXT: RelCall,RelCont | test2 | [[TEST2_USR]]
   test1();
diff --git a/clang/test/Index/Inputs/Headers/a.h b/clang/test/Index/Inputs/Headers/a.h
index 33c341767627..c5cc31bfb3dc 100644
--- a/clang/test/Index/Inputs/Headers/a.h
+++ b/clang/test/Index/Inputs/Headers/a.h
@@ -1,2 +1,2 @@
-int *getA();
+int *getA(void);
 
diff --git a/clang/test/Index/Inputs/Headers/a_extensions.h b/clang/test/Index/Inputs/Headers/a_extensions.h
index 215578754924..1027eee383da 100644
--- a/clang/test/Index/Inputs/Headers/a_extensions.h
+++ b/clang/test/Index/Inputs/Headers/a_extensions.h
@@ -1 +1 @@
-int *getAExtensions();
+int *getAExtensions(void);
diff --git a/clang/test/Index/Inputs/Headers/crash.h b/clang/test/Index/Inputs/Headers/crash.h
index 238359abbe33..76614fe14ade 100644
--- a/clang/test/Index/Inputs/Headers/crash.h
+++ b/clang/test/Index/Inputs/Headers/crash.h
@@ -3,4 +3,4 @@
 #  pragma clang __debug crash
 #endif
 
-const char *getCrashString();
+const char *getCrashString(void);
diff --git a/clang/test/Index/annotate-comments-objc.m b/clang/test/Index/annotate-comments-objc.m
index 471bc2bcb217..b4671519c4d9 100644
--- a/clang/test/Index/annotate-comments-objc.m
+++ b/clang/test/Index/annotate-comments-objc.m
@@ -49,7 +49,7 @@ typedef NS_ENUM(int, An_NS_ENUM_isdoxy1) { Red, Green, Blue };
 // embedded in declarators.
 
 #define DECLARE_FUNCTION() \
-    void functionFromMacro() { \
+    void functionFromMacro(void) { \
       typedef struct Struct_notdoxy Struct_notdoxy; \
     }
 
diff --git a/clang/test/Index/crash-recovery-modules.m b/clang/test/Index/crash-recovery-modules.m
index 82979f794bea..72e25a0fbf5f 100644
--- a/clang/test/Index/crash-recovery-modules.m
+++ b/clang/test/Index/crash-recovery-modules.m
@@ -19,7 +19,7 @@
 #pragma clang __debug crash
 #endif
 
-void test() {
+void test(void) {
   const char* error = getCrashString();
 }
 
diff --git a/clang/test/Index/pragma-diag-reparse.c b/clang/test/Index/pragma-diag-reparse.c
index aa1413cda089..e0ce8387ec60 100644
--- a/clang/test/Index/pragma-diag-reparse.c
+++ b/clang/test/Index/pragma-diag-reparse.c
@@ -12,7 +12,7 @@ int main (int argc, const char * argv[])
 }
 
 #pragma clang diagnostic ignored "-Wmisleading-indentation"
-void foo() { int b=0; while (b==b); }
+void foo(void) { int b=0; while (b==b); }
 
 // RUN: env CINDEXTEST_EDITING=1 CINDEXTEST_FAILONERROR=1 c-index-test -test-load-source-reparse 5 local \
 // RUN: -I%S/Inputs \
diff --git a/clang/test/Index/preamble-reparse-cmd-define.c b/clang/test/Index/preamble-reparse-cmd-define.c
index 3fa76836d614..d3513f55f1e0 100644
--- a/clang/test/Index/preamble-reparse-cmd-define.c
+++ b/clang/test/Index/preamble-reparse-cmd-define.c
@@ -4,6 +4,6 @@
 
 // CHECK-NOT: error:
 
-int foo() {
+int foo(void) {
   return x;
 }
diff --git a/clang/test/Index/preamble-reparse-cmd-define.c.remap b/clang/test/Index/preamble-reparse-cmd-define.c.remap
index 35c140d08211..ab0a0dbdca42 100644
--- a/clang/test/Index/preamble-reparse-cmd-define.c.remap
+++ b/clang/test/Index/preamble-reparse-cmd-define.c.remap
@@ -3,6 +3,6 @@
 #error CMD_MACRO undefined
 #endif 
 
-int foo() {
+int foo(void) {
   return x;
 }
diff --git a/clang/test/Index/preamble-reparse-import.m b/clang/test/Index/preamble-reparse-import.m
index 9bdb89a1dc50..663fc2706e02 100644
--- a/clang/test/Index/preamble-reparse-import.m
+++ b/clang/test/Index/preamble-reparse-import.m
@@ -7,6 +7,6 @@
 
 #import "preamble-reparse-import.m-1.h"
 
-void foo();
+void foo(void);
 #import "preamble-reparse-import.m-2.h"
 #import "preamble-reparse-import.m-1.h"
diff --git a/clang/test/Index/preamble-reparse-warn-macro.c b/clang/test/Index/preamble-reparse-warn-macro.c
index e02fbde78403..d10c1d61d53f 100644
--- a/clang/test/Index/preamble-reparse-warn-macro.c
+++ b/clang/test/Index/preamble-reparse-warn-macro.c
@@ -8,5 +8,5 @@
 #define MAC 1
 #include "header.h"
 
-void test();
+void test(void);
 #define MAC 2
diff --git a/clang/test/Index/warning-flags.c b/clang/test/Index/warning-flags.c
index 2d9a1d99cac9..1694c6abab56 100644
--- a/clang/test/Index/warning-flags.c
+++ b/clang/test/Index/warning-flags.c
@@ -1,4 +1,4 @@
-int foo() { }
+int foo(void) { }
 int *bar(float *f) { return f; }
 
 // RUN: c-index-test -test-load-source all %s 2>&1|FileCheck -check-prefix=CHECK-BOTH-WARNINGS %s
diff --git a/clang/test/Integration/thinlto_profile_sample_accurate.c b/clang/test/Integration/thinlto_profile_sample_accurate.c
index b756829439cf..454242736cf6 100644
--- a/clang/test/Integration/thinlto_profile_sample_accurate.c
+++ b/clang/test/Integration/thinlto_profile_sample_accurate.c
@@ -7,5 +7,5 @@
 
 // CHECK: define{{.*}} void @foo()
 // CHECK: attributes{{.*}} "profile-sample-accurate"
-void foo() {
+void foo(void) {
 }
diff --git a/clang/test/InterfaceStubs/externstatic.c b/clang/test/InterfaceStubs/externstatic.c
index 298dd24a013f..d93e1514bc4c 100644
--- a/clang/test/InterfaceStubs/externstatic.c
+++ b/clang/test/InterfaceStubs/externstatic.c
@@ -24,4 +24,4 @@
 // We want to emit extern function symbols.
 // CHECK-EXTERN2: bar
 STORAGE int foo;
-STORAGE int bar() { return 42; }
+STORAGE int bar(void) { return 42; }
diff --git a/clang/test/InterfaceStubs/inline.c b/clang/test/InterfaceStubs/inline.c
index 1dec4ae677d7..7a30e511d5f3 100644
--- a/clang/test/InterfaceStubs/inline.c
+++ b/clang/test/InterfaceStubs/inline.c
@@ -39,7 +39,7 @@
 // CHECK-STATIC-NOT: foo.var
 // CHECK-STD-NOT: foo
 #pragma clang diagnostic ignored "-Wstatic-local-in-inline"
-INLINE int foo() {
+INLINE int foo(void) {
   static int var = 42;
   return var;
 }
diff --git a/clang/test/InterfaceStubs/inline.h b/clang/test/InterfaceStubs/inline.h
index d8b1b0a617d5..2f8083c98fda 100644
--- a/clang/test/InterfaceStubs/inline.h
+++ b/clang/test/InterfaceStubs/inline.h
@@ -1,5 +1,5 @@
 // REQUIRES: x86-registered-target
-INLINE int bar() {
+INLINE int bar(void) {
   static int var = 42;
   return var;
 }
diff --git a/clang/test/Lexer/c90.c b/clang/test/Lexer/c90.c
index 649173d71dfb..8752404c1c19 100644
--- a/clang/test/Lexer/c90.c
+++ b/clang/test/Lexer/c90.c
@@ -11,7 +11,7 @@ b;}
 
 // comment accepted as extension    /* expected-error {{// comments are not allowed in this language}}
 
-void test2() {
+void test2(void) {
   const char * str =
     "sdjflksdjf lksdjf skldfjsdkljflksdjf kldsjflkdsj fldks jflsdkjfds" // expected-error{{string literal of length 845 exceeds maximum length 509 that C90 compilers are required to support}}
     "sdjflksdjf lksdjf skldfjsdkljflksdjf kldsjflkdsj fldks jflsdkjfds"
@@ -28,13 +28,13 @@ void test2() {
     "sdjflksdjf lksdjf skldfjsdkljflksdjf kldsjflkdsj fldks jflsdkjfds";
 }
 
-void test3() {
+void test3(void) {
   (void)L"\u1234";  // expected-error {{universal character names are only valid in C99 or C++}}
   (void)L'\u1234';  // expected-error {{universal character names are only valid in C99 or C++}}
 }
 
 #define PREFIX(x) foo ## x
-int test4() {
+int test4(void) {
   int PREFIX(0p) = 0;
   int *p = &PREFIX(0p+1);
   return p[-1];
diff --git a/clang/test/Lexer/char-escapes-delimited.c b/clang/test/Lexer/char-escapes-delimited.c
index 62465db464bc..461122dcdb11 100644
--- a/clang/test/Lexer/char-escapes-delimited.c
+++ b/clang/test/Lexer/char-escapes-delimited.c
@@ -15,7 +15,7 @@ const char *errors =
     "\o{8}" //expected-error {{invalid digit '8' in escape sequence}}
     ;
 
-void ucn() {
+void ucn(void) {
   char a = '\u{1234}'; // expected-error {{character too large for enclosing character literal type}}
                        // expected-warning@-1 {{delimited escape sequences are a Clang extension}}
 
@@ -31,7 +31,7 @@ void ucn() {
   unsigned d = U'\u{111111111}';       //expected-error {{hex escape sequence out of range}}
 }
 
-void hex() {
+void hex(void) {
   char a = '\x{1}';             // expected-warning {{extension}}
   char b = '\x{abcdegggggabc}'; // expected-error 5{{invalid digit 'g' in escape sequence}}
   char c = '\x{ff1}';           // expected-error {{hex escape sequence out of range}}
@@ -47,7 +47,7 @@ void hex() {
   unsigned i = U'\x{100000000}'; // expected-error {{hex escape sequence out of range}}
 }
 
-void octal() {
+void octal(void) {
   char a = '\o{1}';              // expected-warning {{extension}}
   char b = '\o{12345678881238}'; // expected-error 4{{invalid digit '8' in escape sequence}}
   char c = '\o{777}';            // //expected-error {{octal escape sequence out of range}}
@@ -60,7 +60,7 @@ void octal() {
 #endif
 }
 
-void concat() {
+void concat(void) {
   (void)"\x{" "12}"; // expected-error {{expected '}'}}
   (void)"\u{" "12}"; // expected-error {{expected '}'}}
   (void)"\o{" "12}"; // expected-error {{expected '}'}}
@@ -70,7 +70,7 @@ void concat() {
   (void)"\o{12" "}"; // expected-error {{expected '}'}}
 }
 
-void separators() {
+void separators(void) {
   (void)"\x{12'3}"; // expected-error {{invalid digit ''' in escape sequence}}
   (void)"\u{12'3}"; // expected-error {{invalid digit ''' in escape sequence}}
   (void)"\o{12'3}"; // expected-error {{invalid digit ''' in escape sequence}}
diff --git a/clang/test/Lexer/conflict-marker.c b/clang/test/Lexer/conflict-marker.c
index 2611827d2ace..36310187a9ca 100644
--- a/clang/test/Lexer/conflict-marker.c
+++ b/clang/test/Lexer/conflict-marker.c
@@ -32,7 +32,7 @@ int z = 2;
 y b;
 
 
-int foo() {
+int foo(void) {
   y a = x;
   return x + a - z;
 }
diff --git a/clang/test/Lexer/ms-extensions.c b/clang/test/Lexer/ms-extensions.c
index de7ef93e6b13..dc7c543f00f8 100644
--- a/clang/test/Lexer/ms-extensions.c
+++ b/clang/test/Lexer/ms-extensions.c
@@ -23,14 +23,14 @@ __complex float c3 = 1.0if;
 #define USHORT 0xffffui16
 #define UCHAR 0xffui8
 
-void a() {
+void a(void) {
 	unsigned long long m = ULLONG_MAX;
 	unsigned int n = UINT;
         unsigned short s = USHORT;
         unsigned char c = UCHAR;
 }
 
-void pr_7968()
+void pr_7968(void)
 {
   int var1 = 0x1111111e+1;
   int var2 = 0X1111111e+1;
diff --git a/clang/test/Lexer/multiple-include.c b/clang/test/Lexer/multiple-include.c
index d737f95db271..25bb22a6dc20 100644
--- a/clang/test/Lexer/multiple-include.c
+++ b/clang/test/Lexer/multiple-include.c
@@ -11,7 +11,7 @@
 #include "multiple-include.c"
 #undef XVID_AUTO_INCLUDE
 
-typedef void ff();
+typedef void ff(void);
 typedef struct { ff *a;} S;
 
 S s = { H_Pass_8_C };
@@ -21,7 +21,7 @@ S s = { H_Pass_8_C };
 #if defined(XVID_AUTO_INCLUDE) && defined(REFERENCE_CODE)
 #elif defined(XVID_AUTO_INCLUDE) && !defined(REFERENCE_CODE)
 
-static void FUNC_H(){};
+static void FUNC_H(void){};
 #undef FUNC_H
 
 #endif
diff --git a/clang/test/Lexer/newline-eof.c b/clang/test/Lexer/newline-eof.c
index 340d9de8d36a..f8471fefac7c 100644
--- a/clang/test/Lexer/newline-eof.c
+++ b/clang/test/Lexer/newline-eof.c
@@ -9,7 +9,7 @@
 // RUN: %clang_cc1 -fsyntax-only -x c++ -std=c++11 -Werror -pedantic %s
 
 // Make sure the diagnostic shows up properly at the end of the last line.
-// CHECK: newline-eof.c:[[@LINE+3]]:63
+// CHECK: newline-eof.c:[[@LINE+3]]:67
 
 // The following line isn't terminated, don't fix it.
-void foo() {} // expected-warning{{no newline at end of file}}
\ No newline at end of file
+void foo(void) {} // expected-warning{{no newline at end of file}}
\ No newline at end of file
diff --git a/clang/test/Lexer/numeric-literal-trash.c b/clang/test/Lexer/numeric-literal-trash.c
index 60981feee16b..c3c6b7308504 100644
--- a/clang/test/Lexer/numeric-literal-trash.c
+++ b/clang/test/Lexer/numeric-literal-trash.c
@@ -7,7 +7,7 @@
 int ec(int, int);
 
 
- void x() {
+ void x(void) {
 
 XRECORD (XRECORD (1, 1), 1);
     }
diff --git a/clang/test/Lexer/objc_macros.m b/clang/test/Lexer/objc_macros.m
index 0223bed4e3b0..c286eb7e1f98 100644
--- a/clang/test/Lexer/objc_macros.m
+++ b/clang/test/Lexer/objc_macros.m
@@ -10,7 +10,7 @@
 // No warning because this is the default expansion anyway.
 
 // Check that this still expands to the right text.
-void test() {
+void test(void) {
   goto label; // expected-error {{cannot jump from this goto statement to its label}}
   __weak id x; // expected-note {{jump bypasses initialization of __weak variable}}
 label:
diff --git a/clang/test/Lexer/pragma-region.c b/clang/test/Lexer/pragma-region.c
index 502db22715a8..ba7e10625b47 100644
--- a/clang/test/Lexer/pragma-region.c
+++ b/clang/test/Lexer/pragma-region.c
@@ -17,7 +17,7 @@
 void foo(void){}
 #pragma endregion long comment
 
-void inner();
+void inner(void);
 
 __pragma(region) // no sense, but ignored
 _Pragma("region")// ditto
diff --git a/clang/test/Lexer/string_concat.cpp b/clang/test/Lexer/string_concat.cpp
index a7eb396fe9f6..916f1e340c46 100644
--- a/clang/test/Lexer/string_concat.cpp
+++ b/clang/test/Lexer/string_concat.cpp
@@ -7,7 +7,7 @@ typedef __CHAR16_TYPE__ char16_t;
 typedef __CHAR32_TYPE__ char32_t;
 #endif
 
-void f() {
+void f(void) {
 
   const char* a = u8"abc" u"abc"; // expected-error {{unsupported non-standard concatenation of string literals}}
   const char* b = u8"abc" U"abc"; // expected-error {{unsupported non-standard concatenation of string literals}}
diff --git a/clang/test/Lexer/unicode.c b/clang/test/Lexer/unicode.c
index 35665681d490..f67b55415f96 100644
--- a/clang/test/Lexer/unicode.c
+++ b/clang/test/Lexer/unicode.c
@@ -55,7 +55,7 @@ extern int 👷‍♀; // expected-warning {{declaration does not declare anythi
 // A 🌹 by any other name....
 extern int 🌹;
 int 🌵(int 🌻) { return 🌻+ 1; }
-int main () {
+int main (void) {
   int 🌷 = 🌵(🌹);
   return 🌷;
 }
diff --git a/clang/test/Lexer/wchar.c b/clang/test/Lexer/wchar.c
index 4ecaee429f73..e6b3467473c7 100644
--- a/clang/test/Lexer/wchar.c
+++ b/clang/test/Lexer/wchar.c
@@ -1,6 +1,6 @@
 // RUN: %clang_cc1 -fsyntax-only -fwchar-type=short -fno-signed-wchar -verify %s
 
-void f() {
+void f(void) {
   (void)L"\U00010000"; // unicode escape produces UTF-16 sequence, so no warning
 
   (void)L'ab';  // expected-error {{wide character literals may not contain multiple characters}}
diff --git a/clang/test/Misc/Inputs/remapped-file-2 b/clang/test/Misc/Inputs/remapped-file-2
index 9ac034a3b979..36b1375832cb 100644
--- a/clang/test/Misc/Inputs/remapped-file-2
+++ b/clang/test/Misc/Inputs/remapped-file-2
@@ -1,3 +1,3 @@
 #include "nonexistent.h"
 
-int *f() { return fp; }
+int *f(void) { return fp; }
diff --git a/clang/test/Misc/caret-diags-macros.c b/clang/test/Misc/caret-diags-macros.c
index 15eebb6d287e..e60ed389e656 100644
--- a/clang/test/Misc/caret-diags-macros.c
+++ b/clang/test/Misc/caret-diags-macros.c
@@ -2,7 +2,7 @@
 
 #define M1(x) x
 #define M2 1;
-void foo() {
+void foo(void) {
   M1(
     M2);
   // CHECK: {{.*}}:7:{{[0-9]+}}: warning: expression result unused
@@ -13,7 +13,7 @@ void foo() {
 #define A(x) x
 #define B(x) A(x)
 #define C(x) B(x)
-void bar() {
+void bar(void) {
   C(1);
   // CHECK: {{.*}}:17:5: warning: expression result unused
 }
@@ -36,7 +36,7 @@ void baz(char *Msg) {
 #define macro_many_args2(x, y, z) macro_many_args1(x, y, z)
 #define macro_many_args3(x, y, z) macro_many_args2(x, y, z)
 
-void test() {
+void test(void) {
   macro_args3(11);
   // CHECK: {{.*}}:40:15: warning: expression result unused
   // Also check that the 'caret' printing agrees with the location here where
@@ -83,7 +83,7 @@ void test() {
 #define variadic_args2(x, ...) variadic_args1(x, __VA_ARGS__)
 #define variadic_args3(x, y, ...) variadic_args2(x, y, __VA_ARGS__)
 
-void test2() {
+void test2(void) {
   variadic_args3(1, 22, 3, 4);
   // CHECK: {{.*}}:87:21: warning: expression result unused
   // CHECK-NEXT:      variadic_args3(1, 22, 3, 4);
@@ -99,7 +99,7 @@ void test2() {
 #define variadic_pasting_args3(x, y, ...) variadic_pasting_args2(x, y, __VA_ARGS__)
 #define variadic_pasting_args3a(x, y, ...) variadic_pasting_args2a(x, y, __VA_ARGS__)
 
-void test3() {
+void test3(void) {
   variadic_pasting_args3(1, 2, 3, 4);
   // CHECK: {{.*}}:103:32: warning: expression result unused
   // CHECK: {{.*}}:99:72: note: expanded from macro 'variadic_pasting_args3'
diff --git a/clang/test/Misc/clear-ast-before-backend.c b/clang/test/Misc/clear-ast-before-backend.c
index ba564dc378c1..ead640854cc4 100644
--- a/clang/test/Misc/clear-ast-before-backend.c
+++ b/clang/test/Misc/clear-ast-before-backend.c
@@ -11,4 +11,4 @@
 // STATS: 1 Function decls
 // STATS: Total bytes =
 
-void f() {}
+void f(void) {}
diff --git a/clang/test/Misc/diag-macro-backtrace2.c b/clang/test/Misc/diag-macro-backtrace2.c
index b90dfa16900f..5faed145e49f 100644
--- a/clang/test/Misc/diag-macro-backtrace2.c
+++ b/clang/test/Misc/diag-macro-backtrace2.c
@@ -10,7 +10,7 @@
 #define g(x) h(x)
 #define h(x) x
 
-void PR16799() {
+void PR16799(void) {
   const char str[] = "string";
   a(str);
   // CHECK: :15:3: error: invalid operands to binary expression
diff --git a/clang/test/Misc/loop-opt-setup.c b/clang/test/Misc/loop-opt-setup.c
index 63a6972b82a0..2ef9f25fb0dd 100644
--- a/clang/test/Misc/loop-opt-setup.c
+++ b/clang/test/Misc/loop-opt-setup.c
@@ -14,7 +14,7 @@ int foo(void) {
 // CHECK-LABEL: foo
 // CHECK-NOT: br i1
 
-void Helper() {
+void Helper(void) {
   const int *nodes[5];
   int num_active = 5;
 
diff --git a/clang/test/Misc/printer.c b/clang/test/Misc/printer.c
index 339dda4b4e56..06fff0de1e7f 100644
--- a/clang/test/Misc/printer.c
+++ b/clang/test/Misc/printer.c
@@ -2,4 +2,4 @@
 // RUN: %clang_cc1 -emit-llvm -fexperimental-new-pass-manager -mllvm -print-after-all %s -o %t 2>&1 | FileCheck %s --check-prefix=CHECK-AFTER
 // CHECK-BEFORE: *** IR Dump Before AlwaysInlinerPass
 // CHECK-AFTER: *** IR Dump After AlwaysInlinerPass
-void foo() {}
+void foo(void) {}
diff --git a/clang/test/Misc/remap-file.c b/clang/test/Misc/remap-file.c
index 003cd2e469fd..a2a56d9f18b4 100644
--- a/clang/test/Misc/remap-file.c
+++ b/clang/test/Misc/remap-file.c
@@ -4,5 +4,5 @@
 
 // CHECK-EXIST: remap-file.c:1:28: warning: incompatible pointer types
 // CHECK-NONEXIST: nonexistent.c:1:28: warning: incompatible pointer types
-// CHECK-HEADER: nonexistent.c:3:19: warning: incompatible pointer types
+// CHECK-HEADER: nonexistent.c:3:23: warning: incompatible pointer types
 int
diff --git a/clang/test/Misc/serialized-diags-driver.c b/clang/test/Misc/serialized-diags-driver.c
index 9b580317f3cf..cadf0d864f28 100644
--- a/clang/test/Misc/serialized-diags-driver.c
+++ b/clang/test/Misc/serialized-diags-driver.c
@@ -15,7 +15,7 @@
 // CHECK: note: initialize the variable 'voodoo' to silence this warning []
 // CHECK: Number of diagnostics: 2
 
-void foo() {
+void foo(void) {
   int voodoo;
   voodoo = voodoo + 1;
 }
diff --git a/clang/test/Misc/serialized-diags-no-issue.c b/clang/test/Misc/serialized-diags-no-issue.c
index 5c7da8267db9..675d33c1fe99 100644
--- a/clang/test/Misc/serialized-diags-no-issue.c
+++ b/clang/test/Misc/serialized-diags-no-issue.c
@@ -1,4 +1,4 @@
-void foo();
+void foo(void);
 
 // RUN: %clang -Wall -fsyntax-only %s --serialize-diagnostics %t
 // RUN: c-index-test -read-diagnostics %t 2>&1 | FileCheck %s
diff --git a/clang/test/Misc/serialized-diags-single-issue.c b/clang/test/Misc/serialized-diags-single-issue.c
index 938dda3f0de7..2d18aabda74d 100644
--- a/clang/test/Misc/serialized-diags-single-issue.c
+++ b/clang/test/Misc/serialized-diags-single-issue.c
@@ -1,4 +1,4 @@
-void foo() {
+void foo(void) {
   int voodoo;
   voodoo = voodoo + 1;
 }
diff --git a/clang/test/Misc/serialized-diags-stable.c b/clang/test/Misc/serialized-diags-stable.c
index e05e3f01b6a5..e8ee83ec7499 100644
--- a/clang/test/Misc/serialized-diags-stable.c
+++ b/clang/test/Misc/serialized-diags-stable.c
@@ -4,7 +4,7 @@
 
 // RUN: c-index-test -read-diagnostics %S/Inputs/serialized-diags-stable.dia 2>&1 | FileCheck %s
 
-int foo() {
+int foo(void) {
   // CHECK: serialized-diags-stable.c:[[@LINE+2]]:1: warning: non-void function does not return a value [-Wreturn-type] [Semantic Issue]
   // CHECK-NEXT: Number FIXITs = 0
 }
@@ -13,7 +13,7 @@ int foo() {
 // CHECK-NEXT: Number FIXITs = 0
 // CHECK-NEXT: +-{{.*}}serialized-diags-stable.c:[[@LINE+2]]:6: note: previous definition is here [] []
 // CHECK-NEXT: Number FIXITs = 0
-void bar() {}
+void bar(void) {}
 typedef int bar;
 
 
diff --git a/clang/test/Misc/serialized-diags.c b/clang/test/Misc/serialized-diags.c
index 2f4b86fb42f9..5d21ba30b6c6 100644
--- a/clang/test/Misc/serialized-diags.c
+++ b/clang/test/Misc/serialized-diags.c
@@ -1,15 +1,15 @@
-void foo() {
+void foo(void) {
   int voodoo;
   voodoo = voodoo + 1;
 }
 
-void bar() {
+void bar(void) {
   int dragon;
   dragon = dragon + 1
 }
 
 // Test handling of FixIts that only remove text.
-int baz();
+int baz(void);
 void qux(int x) {
   if ((x == baz()))
    return;
@@ -18,7 +18,7 @@ void qux(int x) {
 // Test handling of macros.
 void taz(int x, int y);
 #define false 0
-void testMacro() {
+void testMacro(void) {
   taz(0, 0, false);
 }
 
@@ -26,7 +26,7 @@ void testMacro() {
 #include "serialized-diags.h"
 
 // Test handling of warnings that have empty fixits.
-void rdar11040133() {
+void rdar11040133(void) {
   unsigned x;
 }
 
diff --git a/clang/test/Misc/wrong-encoding.c b/clang/test/Misc/wrong-encoding.c
index c48402d2a132..9a303ec7e7e9 100644
--- a/clang/test/Misc/wrong-encoding.c
+++ b/clang/test/Misc/wrong-encoding.c
@@ -1,7 +1,7 @@
 // RUN: %clang_cc1 -fsyntax-only -Wno-unused-value %s 2>&1 | FileCheck -strict-whitespace %s
 // REQUIRES: asserts
 
-void foo() {
+void foo(void) {
 
   "��"; // �
 // CHECK: {{^  "<A7><C3>"; // <F8>}}
diff --git a/clang/test/Misc/wrong-encoding2.c b/clang/test/Misc/wrong-encoding2.c
index b60ed7f92b86..92bcb59181de 100644
--- a/clang/test/Misc/wrong-encoding2.c
+++ b/clang/test/Misc/wrong-encoding2.c
@@ -1,7 +1,7 @@
 // RUN: %clang_cc1 -fsyntax-only -fmessage-length=100 %s 2>&1 | FileCheck -strict-whitespace %s
 // REQUIRES: asserts
 
-int main() {
+int main(void) {
     "�#x#p)6�)ѽ�$��>U �h����|� থϻg�Y|`?�;;ƿVj�\\����ݪW9���:̊O�E�ېy?SK�y�����i&n";
 }