diff --git a/lib/AST/ASTContext.cpp b/lib/AST/ASTContext.cpp
index c1bbc5f085..c72c239320 100644
--- a/lib/AST/ASTContext.cpp
+++ b/lib/AST/ASTContext.cpp
@@ -1670,8 +1670,16 @@ TypeInfo ASTContext::getTypeInfoImpl(const Type *T) const {
       break;
     }
 
-    if (const EnumType *ET = dyn_cast<EnumType>(TT))
-      return getTypeInfo(ET->getDecl()->getIntegerType());
+    if (const EnumType *ET = dyn_cast<EnumType>(TT)) {
+      const EnumDecl *ED = ET->getDecl();
+      TypeInfo Info =
+          getTypeInfo(ED->getIntegerType()->getUnqualifiedDesugaredType());
+      if (unsigned AttrAlign = ED->getMaxAlignment()) {
+        Info.Align = AttrAlign;
+        Info.AlignIsRequired = true;
+      }
+      return Info;
+    }
 
     const RecordType *RT = cast<RecordType>(TT);
     const ASTRecordLayout &Layout = getASTRecordLayout(RT->getDecl());
@@ -1786,6 +1794,8 @@ unsigned ASTContext::getPreferredTypeAlign(const Type *T) const {
   T = T->getBaseElementTypeUnsafe();
   if (const ComplexType *CT = T->getAs<ComplexType>())
     T = CT->getElementType().getTypePtr();
+  if (const EnumType *ET = T->getAs<EnumType>())
+    T = ET->getDecl()->getIntegerType().getTypePtr();
   if (T->isSpecificBuiltinType(BuiltinType::Double) ||
       T->isSpecificBuiltinType(BuiltinType::LongLong) ||
       T->isSpecificBuiltinType(BuiltinType::ULongLong))
diff --git a/lib/Sema/SemaDeclAttr.cpp b/lib/Sema/SemaDeclAttr.cpp
index c17451eaaa..c083e9ed6c 100644
--- a/lib/Sema/SemaDeclAttr.cpp
+++ b/lib/Sema/SemaDeclAttr.cpp
@@ -2953,12 +2953,15 @@ void Sema::AddAlignedAttr(SourceRange AttrRange, Decl *D, TypeSourceInfo *TS,
 void Sema::CheckAlignasUnderalignment(Decl *D) {
   assert(D->hasAttrs() && "no attributes on decl");
 
-  QualType Ty;
-  if (ValueDecl *VD = dyn_cast<ValueDecl>(D))
-    Ty = VD->getType();
-  else
-    Ty = Context.getTagDeclType(cast<TagDecl>(D));
-  if (Ty->isDependentType() || Ty->isIncompleteType())
+  QualType UnderlyingTy, DiagTy;
+  if (ValueDecl *VD = dyn_cast<ValueDecl>(D)) {
+    UnderlyingTy = DiagTy = VD->getType();
+  } else {
+    UnderlyingTy = DiagTy = Context.getTagDeclType(cast<TagDecl>(D));
+    if (EnumDecl *ED = dyn_cast<EnumDecl>(D))
+      UnderlyingTy = ED->getIntegerType();
+  }
+  if (DiagTy->isDependentType() || DiagTy->isIncompleteType())
     return;
 
   // C++11 [dcl.align]p5, C11 6.7.5/4:
@@ -2977,10 +2980,10 @@ void Sema::CheckAlignasUnderalignment(Decl *D) {
 
   if (AlignasAttr && Align) {
     CharUnits RequestedAlign = Context.toCharUnitsFromBits(Align);
-    CharUnits NaturalAlign = Context.getTypeAlignInChars(Ty);
+    CharUnits NaturalAlign = Context.getTypeAlignInChars(UnderlyingTy);
     if (NaturalAlign > RequestedAlign)
       Diag(AlignasAttr->getLocation(), diag::err_alignas_underaligned)
-        << Ty << (unsigned)NaturalAlign.getQuantity();
+        << DiagTy << (unsigned)NaturalAlign.getQuantity();
   }
 }
 
diff --git a/test/CXX/dcl.dcl/dcl.attr/dcl.align/p5.cpp b/test/CXX/dcl.dcl/dcl.attr/dcl.align/p5.cpp
index 3c250f9d25..e713d72dc5 100644
--- a/test/CXX/dcl.dcl/dcl.attr/dcl.align/p5.cpp
+++ b/test/CXX/dcl.dcl/dcl.attr/dcl.align/p5.cpp
@@ -15,6 +15,12 @@ enum alignas(1) E1 {}; // expected-error {{requested alignment is less than mini
 enum alignas(1) E2 : char {}; // ok
 enum alignas(4) E3 { e3 = 0 }; // ok
 enum alignas(4) E4 { e4 = 1ull << 33 }; // expected-error {{requested alignment is less than minimum alignment of 8 for type 'E4'}}
+enum alignas(8) E5 {};
+static_assert(alignof(E5) == 8, "");
+
+typedef __attribute__((aligned(16))) int IntAlign16;
+enum E6 : IntAlign16 {};
+static_assert(alignof(E6) == 4, "");
 
 struct S1 {
   alignas(8) int n;
diff --git a/test/Sema/align-x86.c b/test/Sema/align-x86.c
index f112c6398c..e3b8c704b8 100644
--- a/test/Sema/align-x86.c
+++ b/test/Sema/align-x86.c
@@ -27,6 +27,8 @@ double g6[3];
 short chk1[__alignof__(g6) == 8 ? 1 : -1];
 short chk2[__alignof__(double[3]) == 8 ? 1 : -1];
 
+enum { x = 18446744073709551615ULL } g7;
+short chk1[__alignof__(g7) == 8 ? 1 : -1];
 
 // PR5637