diff --git a/include/clang/AST/DeclCXX.h b/include/clang/AST/DeclCXX.h
index 46434c4c7b..06ecd3c373 100644
--- a/include/clang/AST/DeclCXX.h
+++ b/include/clang/AST/DeclCXX.h
@@ -3140,6 +3140,77 @@ public:
   friend class ASTDeclWriter;
 };
 
+/// Represents a pack of using declarations that a single
+/// using-declarator pack-expanded into.
+///
+/// \code
+/// template<typename ...T> struct X : T... {
+///   using T::operator()...;
+///   using T::operator T...;
+/// };
+/// \endcode
+///
+/// In the second case above, the UsingPackDecl will have the name
+/// 'operator T' (which contains an unexpanded pack), but the individual
+/// UsingDecls and UsingShadowDecls will have more reasonable names.
+class UsingPackDecl final
+    : public NamedDecl, public Mergeable<UsingPackDecl>,
+      private llvm::TrailingObjects<UsingPackDecl, NamedDecl *> {
+  void anchor() override;
+
+  /// The UnresolvedUsingValueDecl or UnresolvedUsingTypenameDecl from
+  /// which this waas instantiated.
+  NamedDecl *InstantiatedFrom;
+
+  /// The number of using-declarations created by this pack expansion.
+  unsigned NumExpansions;
+
+  UsingPackDecl(DeclContext *DC, NamedDecl *InstantiatedFrom,
+                ArrayRef<NamedDecl *> UsingDecls)
+      : NamedDecl(UsingPack, DC,
+                  InstantiatedFrom ? InstantiatedFrom->getLocation()
+                                   : SourceLocation(),
+                  InstantiatedFrom ? InstantiatedFrom->getDeclName()
+                                   : DeclarationName()),
+        InstantiatedFrom(InstantiatedFrom), NumExpansions(UsingDecls.size()) {
+    std::uninitialized_copy(UsingDecls.begin(), UsingDecls.end(),
+                            getTrailingObjects<NamedDecl *>());
+  }
+
+public:
+  /// Get the using declaration from which this was instantiated. This will
+  /// always be an UnresolvedUsingValueDecl or an UnresolvedUsingTypenameDecl
+  /// that is a pack expansion.
+  NamedDecl *getInstantiatedFromUsingDecl() { return InstantiatedFrom; }
+
+  /// Get the set of using declarations that this pack expanded into. Note that
+  /// some of these may still be unresolved.
+  ArrayRef<NamedDecl *> expansions() const {
+    return llvm::makeArrayRef(getTrailingObjects<NamedDecl *>(), NumExpansions);
+  }
+
+  static UsingPackDecl *Create(ASTContext &C, DeclContext *DC,
+                               NamedDecl *InstantiatedFrom,
+                               ArrayRef<NamedDecl *> UsingDecls);
+
+  static UsingPackDecl *CreateDeserialized(ASTContext &C, unsigned ID,
+                                           unsigned NumExpansions);
+
+  SourceRange getSourceRange() const override LLVM_READONLY {
+    return InstantiatedFrom->getSourceRange();
+  }
+
+  UsingPackDecl *getCanonicalDecl() override { return getFirstDecl(); }
+  const UsingPackDecl *getCanonicalDecl() const { return getFirstDecl(); }
+
+  static bool classof(const Decl *D) { return classofKind(D->getKind()); }
+  static bool classofKind(Kind K) { return K == UsingPack; }
+
+  friend class ASTDeclReader;
+  friend class ASTDeclWriter;
+  friend TrailingObjects;
+};
+
 /// \brief Represents a dependent using declaration which was not marked with
 /// \c typename.
 ///
@@ -3158,6 +3229,9 @@ class UnresolvedUsingValueDecl : public ValueDecl,
   /// \brief The source location of the 'using' keyword
   SourceLocation UsingLocation;
 
+  /// \brief If this is a pack expansion, the location of the '...'.
+  SourceLocation EllipsisLoc;
+
   /// \brief The nested-name-specifier that precedes the name.
   NestedNameSpecifierLoc QualifierLoc;
 
@@ -3168,11 +3242,12 @@ class UnresolvedUsingValueDecl : public ValueDecl,
   UnresolvedUsingValueDecl(DeclContext *DC, QualType Ty,
                            SourceLocation UsingLoc,
                            NestedNameSpecifierLoc QualifierLoc,
-                           const DeclarationNameInfo &NameInfo)
+                           const DeclarationNameInfo &NameInfo,
+                           SourceLocation EllipsisLoc)
     : ValueDecl(UnresolvedUsingValue, DC,
                 NameInfo.getLoc(), NameInfo.getName(), Ty),
-      UsingLocation(UsingLoc), QualifierLoc(QualifierLoc),
-      DNLoc(NameInfo.getInfo())
+      UsingLocation(UsingLoc), EllipsisLoc(EllipsisLoc),
+      QualifierLoc(QualifierLoc), DNLoc(NameInfo.getInfo())
   { }
 
 public:
@@ -3198,10 +3273,20 @@ public:
     return DeclarationNameInfo(getDeclName(), getLocation(), DNLoc);
   }
 
+  /// \brief Determine whether this is a pack expansion.
+  bool isPackExpansion() const {
+    return EllipsisLoc.isValid();
+  }
+
+  /// \brief Get the location of the ellipsis if this is a pack expansion.
+  SourceLocation getEllipsisLoc() const {
+    return EllipsisLoc;
+  }
+
   static UnresolvedUsingValueDecl *
     Create(ASTContext &C, DeclContext *DC, SourceLocation UsingLoc,
            NestedNameSpecifierLoc QualifierLoc,
-           const DeclarationNameInfo &NameInfo);
+           const DeclarationNameInfo &NameInfo, SourceLocation EllipsisLoc);
 
   static UnresolvedUsingValueDecl *
   CreateDeserialized(ASTContext &C, unsigned ID);
@@ -3242,6 +3327,9 @@ class UnresolvedUsingTypenameDecl
   /// \brief The source location of the 'typename' keyword
   SourceLocation TypenameLocation;
 
+  /// \brief If this is a pack expansion, the location of the '...'.
+  SourceLocation EllipsisLoc;
+
   /// \brief The nested-name-specifier that precedes the name.
   NestedNameSpecifierLoc QualifierLoc;
 
@@ -3249,10 +3337,12 @@ class UnresolvedUsingTypenameDecl
                               SourceLocation TypenameLoc,
                               NestedNameSpecifierLoc QualifierLoc,
                               SourceLocation TargetNameLoc,
-                              IdentifierInfo *TargetName)
+                              IdentifierInfo *TargetName,
+                              SourceLocation EllipsisLoc)
     : TypeDecl(UnresolvedUsingTypename, DC, TargetNameLoc, TargetName,
                UsingLoc),
-      TypenameLocation(TypenameLoc), QualifierLoc(QualifierLoc) { }
+      TypenameLocation(TypenameLoc), EllipsisLoc(EllipsisLoc),
+      QualifierLoc(QualifierLoc) { }
 
   friend class ASTDeclReader;
 
@@ -3272,10 +3362,25 @@ public:
     return QualifierLoc.getNestedNameSpecifier();
   }
 
+  DeclarationNameInfo getNameInfo() const {
+    return DeclarationNameInfo(getDeclName(), getLocation());
+  }
+
+  /// \brief Determine whether this is a pack expansion.
+  bool isPackExpansion() const {
+    return EllipsisLoc.isValid();
+  }
+
+  /// \brief Get the location of the ellipsis if this is a pack expansion.
+  SourceLocation getEllipsisLoc() const {
+    return EllipsisLoc;
+  }
+
   static UnresolvedUsingTypenameDecl *
     Create(ASTContext &C, DeclContext *DC, SourceLocation UsingLoc,
            SourceLocation TypenameLoc, NestedNameSpecifierLoc QualifierLoc,
-           SourceLocation TargetNameLoc, DeclarationName TargetName);
+           SourceLocation TargetNameLoc, DeclarationName TargetName,
+           SourceLocation EllipsisLoc);
 
   static UnresolvedUsingTypenameDecl *
   CreateDeserialized(ASTContext &C, unsigned ID);
diff --git a/include/clang/AST/RecursiveASTVisitor.h b/include/clang/AST/RecursiveASTVisitor.h
index 058ab1fcbe..afacfd5723 100644
--- a/include/clang/AST/RecursiveASTVisitor.h
+++ b/include/clang/AST/RecursiveASTVisitor.h
@@ -1505,6 +1505,8 @@ DEF_TRAVERSE_DECL(UsingDecl, {
   TRY_TO(TraverseDeclarationNameInfo(D->getNameInfo()));
 })
 
+DEF_TRAVERSE_DECL(UsingPackDecl, {})
+
 DEF_TRAVERSE_DECL(UsingDirectiveDecl, {
   TRY_TO(TraverseNestedNameSpecifierLoc(D->getQualifierLoc()));
 })
diff --git a/include/clang/Basic/DeclNodes.td b/include/clang/Basic/DeclNodes.td
index 6da2c2c3d6..7b581d3eec 100644
--- a/include/clang/Basic/DeclNodes.td
+++ b/include/clang/Basic/DeclNodes.td
@@ -67,6 +67,7 @@ def Named : Decl<1>;
     def TemplateTemplateParm : DDecl<Template>;
     def BuiltinTemplate : DDecl<Template>;
   def Using : DDecl<Named>;
+  def UsingPack : DDecl<Named>;
   def UsingShadow : DDecl<Named>;
     def ConstructorUsingShadow : DDecl<UsingShadow>;
   def ObjCMethod : DDecl<Named>, DeclContext;
diff --git a/include/clang/Basic/DiagnosticParseKinds.td b/include/clang/Basic/DiagnosticParseKinds.td
index 31e55b4aff..0943feae95 100644
--- a/include/clang/Basic/DiagnosticParseKinds.td
+++ b/include/clang/Basic/DiagnosticParseKinds.td
@@ -740,6 +740,8 @@ def err_alias_declaration_not_identifier : Error<
   "name defined in alias declaration must be an identifier">;
 def err_alias_declaration_specialization : Error<
   "%select{partial specialization|explicit specialization|explicit instantiation}0 of alias templates is not permitted">;
+def err_alias_declaration_pack_expansion : Error<
+  "alias declaration cannot be a pack expansion">;
 
 // C++1z using-declaration pack expansions
 def ext_multi_using_declaration : ExtWarn<
@@ -749,6 +751,11 @@ def warn_cxx1z_compat_multi_using_declaration : Warning<
   "use of multiple declarators in a single using declaration is "
   "incompatible with C++ standards before C++1z">,
   InGroup<CXXPre1zCompat>, DefaultIgnore;
+def ext_using_declaration_pack : ExtWarn<
+  "pack expansion of using declaration is a C++1z extension">, InGroup<CXX1z>;
+def warn_cxx1z_compat_using_declaration_pack : Warning<
+  "pack expansion using declaration is incompatible with C++ standards "
+  "before C++1z">, InGroup<CXXPre1zCompat>, DefaultIgnore;
 
 // C++11 override control
 def ext_override_control_keyword : ExtWarn<
diff --git a/include/clang/Basic/DiagnosticSemaKinds.td b/include/clang/Basic/DiagnosticSemaKinds.td
index 69322f0f75..f32364e9af 100644
--- a/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/include/clang/Basic/DiagnosticSemaKinds.td
@@ -474,6 +474,8 @@ def err_using_decl_conflict : Error<
 def err_using_decl_conflict_reverse : Error<
   "declaration conflicts with target of using declaration already in scope">;
 def note_using_decl : Note<"%select{|previous }0using declaration">;
+def err_using_decl_redeclaration_expansion : Error<
+  "using declaration pack expansion at block scope produces multiple values">;
 
 def warn_access_decl_deprecated : Warning<
   "access declarations are deprecated; use using declarations instead">,
@@ -4155,6 +4157,9 @@ def err_variable_instantiates_to_function : Error<
 def err_nested_name_spec_non_tag : Error<
   "type %0 cannot be used prior to '::' because it has no members">;
 
+def err_using_pack_expansion_empty : Error<
+  "%select{|member}0 using declaration %1 instantiates to an empty pack">;
+
 // C++ Explicit Instantiation
 def err_explicit_instantiation_duplicate : Error<
     "duplicate explicit instantiation of %0">;
diff --git a/include/clang/Parse/Parser.h b/include/clang/Parse/Parser.h
index 3d098fab84..972f13daca 100644
--- a/include/clang/Parse/Parser.h
+++ b/include/clang/Parse/Parser.h
@@ -2436,9 +2436,10 @@ private:
     CXXScopeSpec SS;
     SourceLocation TemplateKWLoc;
     UnqualifiedId Name;
+    SourceLocation EllipsisLoc;
 
     void clear() {
-      TypenameLoc = TemplateKWLoc = SourceLocation();
+      TypenameLoc = TemplateKWLoc = EllipsisLoc = SourceLocation();
       SS.clear();
       Name.clear();
     }
@@ -2450,9 +2451,6 @@ private:
                                        SourceLocation UsingLoc,
                                        SourceLocation &DeclEnd,
                                        AccessSpecifier AS = AS_none);
-  Decl *ParseAliasTemplate(const ParsedTemplateInfo &TemplateInfo,
-                           SourceLocation &DeclEnd, AccessSpecifier AS,
-                           ParsedAttributesWithRange &MisplacedAttrs1);
   Decl *ParseAliasDeclarationAfterDeclarator(
       const ParsedTemplateInfo &TemplateInfo, SourceLocation UsingLoc,
       UsingDeclarator &D, SourceLocation &DeclEnd, AccessSpecifier AS,
diff --git a/include/clang/Sema/Sema.h b/include/clang/Sema/Sema.h
index 136f848338..ebbc1e1b3e 100644
--- a/include/clang/Sema/Sema.h
+++ b/include/clang/Sema/Sema.h
@@ -4324,12 +4324,15 @@ public:
 
   NamedDecl *BuildUsingDeclaration(Scope *S, AccessSpecifier AS,
                                    SourceLocation UsingLoc,
+                                   bool HasTypenameKeyword,
+                                   SourceLocation TypenameLoc,
                                    CXXScopeSpec &SS,
                                    DeclarationNameInfo NameInfo,
+                                   SourceLocation EllipsisLoc,
                                    AttributeList *AttrList,
-                                   bool IsInstantiation,
-                                   bool HasTypenameKeyword,
-                                   SourceLocation TypenameLoc);
+                                   bool IsInstantiation);
+  NamedDecl *BuildUsingPackDecl(NamedDecl *InstantiatedFrom,
+                                ArrayRef<NamedDecl *> Expansions);
 
   bool CheckInheritingConstructorUsingDecl(UsingDecl *UD);
 
@@ -4343,10 +4346,11 @@ public:
   Decl *ActOnUsingDeclaration(Scope *CurScope,
                               AccessSpecifier AS,
                               SourceLocation UsingLoc,
+                              SourceLocation TypenameLoc,
                               CXXScopeSpec &SS,
                               UnqualifiedId &Name,
-                              AttributeList *AttrList,
-                              SourceLocation TypenameLoc);
+                              SourceLocation EllipsisLoc,
+                              AttributeList *AttrList);
   Decl *ActOnAliasDeclaration(Scope *CurScope,
                               AccessSpecifier AS,
                               MultiTemplateParamsArg TemplateParams,
@@ -6351,7 +6355,7 @@ public:
   ///
   /// \param SS The nested-name-specifier that will be traversed to find
   /// unexpanded parameter packs.
-  void collectUnexpandedParameterPacks(CXXScopeSpec &SS,
+  void collectUnexpandedParameterPacks(NestedNameSpecifierLoc NNS,
                          SmallVectorImpl<UnexpandedParameterPack> &Unexpanded);
 
   /// \brief Collect the set of unexpanded parameter packs within the given
diff --git a/include/clang/Sema/Template.h b/include/clang/Sema/Template.h
index 0d12880354..401bbbf1e5 100644
--- a/include/clang/Sema/Template.h
+++ b/include/clang/Sema/Template.h
@@ -515,6 +515,11 @@ namespace clang {
         VarTemplateDecl *VarTemplate,
         VarTemplatePartialSpecializationDecl *PartialSpec);
     void InstantiateEnumDefinition(EnumDecl *Enum, EnumDecl *Pattern);
+
+  private:
+    template<typename T>
+    Decl *instantiateUnresolvedUsingDecl(T *D,
+                                         bool InstantiatingPackElement = false);
   };  
 }
 
diff --git a/include/clang/Serialization/ASTBitCodes.h b/include/clang/Serialization/ASTBitCodes.h
index 611c00d0e9..4e29ad6a02 100644
--- a/include/clang/Serialization/ASTBitCodes.h
+++ b/include/clang/Serialization/ASTBitCodes.h
@@ -1103,6 +1103,8 @@ namespace clang {
       DECL_NAMESPACE_ALIAS,
       /// \brief A UsingDecl record.
       DECL_USING,
+      /// \brief A UsingPackDecl record.
+      DECL_USING_PACK,
       /// \brief A UsingShadowDecl record.
       DECL_USING_SHADOW,
       /// \brief A ConstructorUsingShadowDecl record.
diff --git a/lib/AST/DeclBase.cpp b/lib/AST/DeclBase.cpp
index 8deef3343d..6111abab64 100644
--- a/lib/AST/DeclBase.cpp
+++ b/lib/AST/DeclBase.cpp
@@ -651,11 +651,13 @@ unsigned Decl::getIdentifierNamespaceForKind(Kind DeclKind) {
     case Typedef:
     case TypeAlias:
     case TypeAliasTemplate:
-    case UnresolvedUsingTypename:
     case TemplateTypeParm:
     case ObjCTypeParam:
       return IDNS_Ordinary | IDNS_Type;
 
+    case UnresolvedUsingTypename:
+      return IDNS_Ordinary | IDNS_Type | IDNS_Using;
+
     case UsingShadow:
       return 0; // we'll actually overwrite this later
 
@@ -663,6 +665,7 @@ unsigned Decl::getIdentifierNamespaceForKind(Kind DeclKind) {
       return IDNS_Ordinary | IDNS_Using;
 
     case Using:
+    case UsingPack:
       return IDNS_Using;
 
     case ObjCProtocol:
diff --git a/lib/AST/DeclCXX.cpp b/lib/AST/DeclCXX.cpp
index 8563416a48..1860b948d6 100644
--- a/lib/AST/DeclCXX.cpp
+++ b/lib/AST/DeclCXX.cpp
@@ -2250,15 +2250,37 @@ SourceRange UsingDecl::getSourceRange() const {
   return SourceRange(Begin, getNameInfo().getEndLoc());
 }
 
+void UsingPackDecl::anchor() { }
+
+UsingPackDecl *UsingPackDecl::Create(ASTContext &C, DeclContext *DC,
+                                     NamedDecl *InstantiatedFrom,
+                                     ArrayRef<NamedDecl *> UsingDecls) {
+  size_t Extra = additionalSizeToAlloc<NamedDecl *>(UsingDecls.size());
+  return new (C, DC, Extra) UsingPackDecl(DC, InstantiatedFrom, UsingDecls);
+}
+
+UsingPackDecl *UsingPackDecl::CreateDeserialized(ASTContext &C, unsigned ID,
+                                                 unsigned NumExpansions) {
+  size_t Extra = additionalSizeToAlloc<NamedDecl *>(NumExpansions);
+  auto *Result = new (C, ID, Extra) UsingPackDecl(nullptr, nullptr, None);
+  Result->NumExpansions = NumExpansions;
+  auto *Trail = Result->getTrailingObjects<NamedDecl *>();
+  for (unsigned I = 0; I != NumExpansions; ++I)
+    new (Trail + I) NamedDecl*(nullptr);
+  return Result;
+}
+
 void UnresolvedUsingValueDecl::anchor() { }
 
 UnresolvedUsingValueDecl *
 UnresolvedUsingValueDecl::Create(ASTContext &C, DeclContext *DC,
                                  SourceLocation UsingLoc,
                                  NestedNameSpecifierLoc QualifierLoc,
-                                 const DeclarationNameInfo &NameInfo) {
+                                 const DeclarationNameInfo &NameInfo,
+                                 SourceLocation EllipsisLoc) {
   return new (C, DC) UnresolvedUsingValueDecl(DC, C.DependentTy, UsingLoc,
-                                              QualifierLoc, NameInfo);
+                                              QualifierLoc, NameInfo,
+                                              EllipsisLoc);
 }
 
 UnresolvedUsingValueDecl *
@@ -2266,7 +2288,8 @@ UnresolvedUsingValueDecl::CreateDeserialized(ASTContext &C, unsigned ID) {
   return new (C, ID) UnresolvedUsingValueDecl(nullptr, QualType(),
                                               SourceLocation(),
                                               NestedNameSpecifierLoc(),
-                                              DeclarationNameInfo());
+                                              DeclarationNameInfo(),
+                                              SourceLocation());
 }
 
 SourceRange UnresolvedUsingValueDecl::getSourceRange() const {
@@ -2283,17 +2306,18 @@ UnresolvedUsingTypenameDecl::Create(ASTContext &C, DeclContext *DC,
                                     SourceLocation TypenameLoc,
                                     NestedNameSpecifierLoc QualifierLoc,
                                     SourceLocation TargetNameLoc,
-                                    DeclarationName TargetName) {
+                                    DeclarationName TargetName,
+                                    SourceLocation EllipsisLoc) {
   return new (C, DC) UnresolvedUsingTypenameDecl(
       DC, UsingLoc, TypenameLoc, QualifierLoc, TargetNameLoc,
-      TargetName.getAsIdentifierInfo());
+      TargetName.getAsIdentifierInfo(), EllipsisLoc);
 }
 
 UnresolvedUsingTypenameDecl *
 UnresolvedUsingTypenameDecl::CreateDeserialized(ASTContext &C, unsigned ID) {
   return new (C, ID) UnresolvedUsingTypenameDecl(
       nullptr, SourceLocation(), SourceLocation(), NestedNameSpecifierLoc(),
-      SourceLocation(), nullptr);
+      SourceLocation(), nullptr, SourceLocation());
 }
 
 void StaticAssertDecl::anchor() { }
diff --git a/lib/CodeGen/CGDecl.cpp b/lib/CodeGen/CGDecl.cpp
index 4657347758..d761363801 100644
--- a/lib/CodeGen/CGDecl.cpp
+++ b/lib/CodeGen/CGDecl.cpp
@@ -113,6 +113,10 @@ void CodeGenFunction::EmitDecl(const Decl &D) {
     if (CGDebugInfo *DI = getDebugInfo())
         DI->EmitUsingDecl(cast<UsingDecl>(D));
     return;
+  case Decl::UsingPack:
+    for (auto *Using : cast<UsingPackDecl>(D).expansions())
+      EmitDecl(*Using);
+    return;
   case Decl::UsingDirective: // using namespace X; [C++]
     if (CGDebugInfo *DI = getDebugInfo())
       DI->EmitUsingDirective(cast<UsingDirectiveDecl>(D));
diff --git a/lib/Parse/ParseDeclCXX.cpp b/lib/Parse/ParseDeclCXX.cpp
index d31d114237..4002b09d2b 100644
--- a/lib/Parse/ParseDeclCXX.cpp
+++ b/lib/Parse/ParseDeclCXX.cpp
@@ -560,7 +560,9 @@ bool Parser::ParseUsingDeclarator(unsigned Context, UsingDeclarator &D) {
   //   nested-name-specifier, the name is [...] considered to name the
   //   constructor.
   if (getLangOpts().CPlusPlus11 && Context == Declarator::MemberContext &&
-      Tok.is(tok::identifier) && NextToken().is(tok::semi) &&
+      Tok.is(tok::identifier) &&
+      (NextToken().is(tok::semi) || NextToken().is(tok::comma) ||
+       NextToken().is(tok::ellipsis)) &&
       D.SS.isNotEmpty() && LastII == Tok.getIdentifierInfo() &&
       !D.SS.getScopeRep()->getAsNamespace() &&
       !D.SS.getScopeRep()->getAsNamespaceAlias()) {
@@ -578,7 +580,10 @@ bool Parser::ParseUsingDeclarator(unsigned Context, UsingDeclarator &D) {
       return true;
   }
 
-  // FIXME: Parse optional ellipsis
+  if (TryConsumeToken(tok::ellipsis, D.EllipsisLoc))
+    Diag(Tok.getLocation(), getLangOpts().CPlusPlus1z ?
+         diag::warn_cxx1z_compat_using_declaration_pack :
+         diag::ext_using_declaration_pack);
 
   return false;
 }
@@ -678,9 +683,9 @@ Parser::ParseUsingDeclaration(unsigned Context,
         D.TypenameLoc = SourceLocation();
       }
 
-      Decl *UD =
-          Actions.ActOnUsingDeclaration(getCurScope(), AS, UsingLoc, D.SS,
-                                        D.Name, Attrs.getList(), D.TypenameLoc);
+      Decl *UD = Actions.ActOnUsingDeclaration(getCurScope(), AS, UsingLoc,
+                                               D.TypenameLoc, D.SS, D.Name,
+                                               D.EllipsisLoc, Attrs.getList());
       if (UD)
         DeclsInGroup.push_back(UD);
     }
@@ -708,62 +713,6 @@ Parser::ParseUsingDeclaration(unsigned Context,
   return Actions.BuildDeclaratorGroup(DeclsInGroup, /*MayContainAuto*/false);
 }
 
-Decl *Parser::ParseAliasTemplate(const ParsedTemplateInfo &TemplateInfo,
-                                 SourceLocation &DeclEnd, AccessSpecifier AS,
-                                 ParsedAttributesWithRange &MisplacedAttrs1) {
-  assert(Tok.is(tok::kw_using) && "Not using token");
-  ObjCDeclContextSwitch ObjCDC(*this);
-  
-  // Eat 'using'.
-  SourceLocation UsingLoc = ConsumeToken();
-  if (Tok.is(tok::code_completion)) {
-    Actions.CodeCompleteUsing(getCurScope());
-    cutOffParsing();
-    return nullptr;
-  }
-
-  // 'using namespace' means this is a using-directive.
-  if (Tok.is(tok::kw_namespace)) {
-    SourceRange R = TemplateInfo.getSourceRange();
-    Diag(UsingLoc, diag::err_templated_using_directive_declaration)
-        << 0 /* directive */ << R;
-    SkipUntil(tok::semi);
-    return nullptr;
-  }
-
-  // Check for misplaced attributes before the identifier.
-  ParsedAttributesWithRange MisplacedAttrs2(AttrFactory);
-  MaybeParseCXX11Attributes(MisplacedAttrs2);
-
-  // FIXME: Just parse an identifier here?
-  UsingDeclarator D;
-  if (ParseUsingDeclarator(Declarator::FileContext, D)) {
-    SkipUntil(tok::semi);
-    return nullptr;
-  }
-
-  ParsedAttributesWithRange Attrs(AttrFactory);
-
-  // If we had any misplaced attributes from earlier, this is where they
-  // should have been written.
-  for (auto *MisplacedAttrs : {&MisplacedAttrs1, &MisplacedAttrs2}) {
-    if (MisplacedAttrs->Range.isValid()) {
-      Diag(MisplacedAttrs->Range.getBegin(), diag::err_attributes_not_allowed)
-        << FixItHint::CreateInsertionFromRange(
-               Tok.getLocation(),
-               CharSourceRange::getTokenRange(MisplacedAttrs->Range))
-        << FixItHint::CreateRemoval(MisplacedAttrs->Range);
-      Attrs.takeAllFrom(*MisplacedAttrs);
-    }
-  }
-
-  MaybeParseGNUAttributes(Attrs);
-  MaybeParseCXX11Attributes(Attrs);
-
-  return ParseAliasDeclarationAfterDeclarator(TemplateInfo, UsingLoc, D,
-                                              DeclEnd, AS, Attrs);
-}
-
 Decl *Parser::ParseAliasDeclarationAfterDeclarator(
     const ParsedTemplateInfo &TemplateInfo, SourceLocation UsingLoc,
     UsingDeclarator &D, SourceLocation &DeclEnd, AccessSpecifier AS,
@@ -813,6 +762,9 @@ Decl *Parser::ParseAliasDeclarationAfterDeclarator(
   else if (D.SS.isNotEmpty())
     Diag(D.SS.getBeginLoc(), diag::err_alias_declaration_not_identifier)
       << FixItHint::CreateRemoval(D.SS.getRange());
+  if (D.EllipsisLoc.isValid())
+    Diag(D.EllipsisLoc, diag::err_alias_declaration_pack_expansion)
+      << FixItHint::CreateRemoval(SourceRange(D.EllipsisLoc));
 
   Decl *DeclFromDeclSpec = nullptr;
   TypeResult TypeAlias =
@@ -2487,8 +2439,9 @@ Parser::ParseCXXClassMemberDeclaration(AccessSpecifier AS,
       }
 
       return DeclGroupPtrTy::make(DeclGroupRef(Actions.ActOnUsingDeclaration(
-          getCurScope(), AS, /*UsingLoc*/SourceLocation(), SS, Name,
-          /*AttrList*/nullptr, /*TypenameLoc*/SourceLocation())));
+          getCurScope(), AS, /*UsingLoc*/ SourceLocation(),
+          /*TypenameLoc*/ SourceLocation(), SS, Name,
+          /*EllipsisLoc*/ SourceLocation(), /*AttrList*/ nullptr)));
     }
   }
 
diff --git a/lib/Sema/SemaDeclCXX.cpp b/lib/Sema/SemaDeclCXX.cpp
index ac643af149..21bdd945f0 100644
--- a/lib/Sema/SemaDeclCXX.cpp
+++ b/lib/Sema/SemaDeclCXX.cpp
@@ -8533,12 +8533,18 @@ void Sema::PushUsingDirective(Scope *S, UsingDirectiveDecl *UDir) {
 Decl *Sema::ActOnUsingDeclaration(Scope *S,
                                   AccessSpecifier AS,
                                   SourceLocation UsingLoc,
+                                  SourceLocation TypenameLoc,
                                   CXXScopeSpec &SS,
                                   UnqualifiedId &Name,
-                                  AttributeList *AttrList,
-                                  SourceLocation TypenameLoc) {
+                                  SourceLocation EllipsisLoc,
+                                  AttributeList *AttrList) {
   assert(S->getFlags() & Scope::DeclScope && "Invalid Scope.");
 
+  if (SS.isEmpty()) {
+    Diag(Name.getLocStart(), diag::err_using_requires_qualname);
+    return nullptr;
+  }
+
   switch (Name.getKind()) {
   case UnqualifiedId::IK_ImplicitSelfParam:
   case UnqualifiedId::IK_Identifier:
@@ -8584,14 +8590,23 @@ Decl *Sema::ActOnUsingDeclaration(Scope *S,
       << FixItHint::CreateInsertion(SS.getRange().getBegin(), "using ");
   }
 
-  if (DiagnoseUnexpandedParameterPack(SS, UPPC_UsingDeclaration) ||
-      DiagnoseUnexpandedParameterPack(TargetNameInfo, UPPC_UsingDeclaration))
-    return nullptr;
+  if (EllipsisLoc.isInvalid()) {
+    if (DiagnoseUnexpandedParameterPack(SS, UPPC_UsingDeclaration) ||
+        DiagnoseUnexpandedParameterPack(TargetNameInfo, UPPC_UsingDeclaration))
+      return nullptr;
+  } else {
+    if (!SS.getScopeRep()->containsUnexpandedParameterPack() &&
+        !TargetNameInfo.containsUnexpandedParameterPack()) {
+      Diag(EllipsisLoc, diag::err_pack_expansion_without_parameter_packs)
+        << SourceRange(SS.getBeginLoc(), TargetNameInfo.getEndLoc());
+      EllipsisLoc = SourceLocation();
+    }
+  }
 
-  NamedDecl *UD = BuildUsingDeclaration(S, AS, UsingLoc, SS,
-                                        TargetNameInfo, AttrList,
-                                        /* IsInstantiation */ false,
-                                        TypenameLoc.isValid(), TypenameLoc);
+  NamedDecl *UD =
+      BuildUsingDeclaration(S, AS, UsingLoc, TypenameLoc.isValid(), TypenameLoc,
+                            SS, TargetNameInfo, EllipsisLoc, AttrList,
+                            /*IsInstantiation*/false);
   if (UD)
     PushOnScopeChains(UD, S, /*AddToContext*/ false);
 
@@ -8654,6 +8669,7 @@ bool Sema::CheckUsingShadowDecl(UsingDecl *Using, NamedDecl *Orig,
              diag::err_using_decl_nested_name_specifier_is_current_class)
           << Using->getQualifierLoc().getSourceRange();
         Diag(Orig->getLocation(), diag::note_using_decl_target);
+        Using->setInvalidDecl();
         return true;
       }
 
@@ -8663,6 +8679,7 @@ bool Sema::CheckUsingShadowDecl(UsingDecl *Using, NamedDecl *Orig,
         << cast<CXXRecordDecl>(CurContext)
         << Using->getQualifierLoc().getSourceRange();
       Diag(Orig->getLocation(), diag::note_using_decl_target);
+      Using->setInvalidDecl();
       return true;
     }
   }
@@ -8686,7 +8703,7 @@ bool Sema::CheckUsingShadowDecl(UsingDecl *Using, NamedDecl *Orig,
     // We can have UsingDecls in our Previous results because we use the same
     // LookupResult for checking whether the UsingDecl itself is a valid
     // redeclaration.
-    if (isa<UsingDecl>(D))
+    if (isa<UsingDecl>(D) || isa<UsingPackDecl>(D))
       continue;
 
     if (IsEquivalentForUsingDecl(Context, D, Target)) {
@@ -8732,6 +8749,7 @@ bool Sema::CheckUsingShadowDecl(UsingDecl *Using, NamedDecl *Orig,
 
     Diag(Target->getLocation(), diag::note_using_decl_target);
     Diag(OldDecl->getLocation(), diag::note_using_decl_conflict);
+    Using->setInvalidDecl();
     return true;
   }
 
@@ -8744,6 +8762,7 @@ bool Sema::CheckUsingShadowDecl(UsingDecl *Using, NamedDecl *Orig,
     Diag(Using->getLocation(), diag::err_using_decl_conflict);
     Diag(Target->getLocation(), diag::note_using_decl_target);
     Diag(Tag->getLocation(), diag::note_using_decl_conflict);
+    Using->setInvalidDecl();
     return true;
   }
 
@@ -8753,6 +8772,7 @@ bool Sema::CheckUsingShadowDecl(UsingDecl *Using, NamedDecl *Orig,
   Diag(Using->getLocation(), diag::err_using_decl_conflict);
   Diag(Target->getLocation(), diag::note_using_decl_target);
   Diag(NonTag->getLocation(), diag::note_using_decl_conflict);
+  Using->setInvalidDecl();
   return true;
 }
 
@@ -8960,23 +8980,19 @@ private:
 ///   the lookup differently for these declarations.
 NamedDecl *Sema::BuildUsingDeclaration(Scope *S, AccessSpecifier AS,
                                        SourceLocation UsingLoc,
+                                       bool HasTypenameKeyword,
+                                       SourceLocation TypenameLoc,
                                        CXXScopeSpec &SS,
                                        DeclarationNameInfo NameInfo,
+                                       SourceLocation EllipsisLoc,
                                        AttributeList *AttrList,
-                                       bool IsInstantiation,
-                                       bool HasTypenameKeyword,
-                                       SourceLocation TypenameLoc) {
+                                       bool IsInstantiation) {
   assert(!SS.isInvalid() && "Invalid CXXScopeSpec.");
   SourceLocation IdentLoc = NameInfo.getLoc();
   assert(IdentLoc.isValid() && "Invalid TargetName location.");
 
   // FIXME: We ignore attributes for now.
 
-  if (SS.isEmpty()) {
-    Diag(IdentLoc, diag::err_using_requires_qualname);
-    return nullptr;
-  }
-
   // For an inheriting constructor declaration, the name of the using
   // declaration is the name of a constructor in this class, not in the
   // base class.
@@ -9042,16 +9058,17 @@ NamedDecl *Sema::BuildUsingDeclaration(Scope *S, AccessSpecifier AS,
   DeclContext *LookupContext = computeDeclContext(SS);
   NamedDecl *D;
   NestedNameSpecifierLoc QualifierLoc = SS.getWithLocInContext(Context);
-  if (!LookupContext) {
+  if (!LookupContext || EllipsisLoc.isValid()) {
     if (HasTypenameKeyword) {
       // FIXME: not all declaration name kinds are legal here
       D = UnresolvedUsingTypenameDecl::Create(Context, CurContext,
                                               UsingLoc, TypenameLoc,
                                               QualifierLoc,
-                                              IdentLoc, NameInfo.getName());
+                                              IdentLoc, NameInfo.getName(),
+                                              EllipsisLoc);
     } else {
       D = UnresolvedUsingValueDecl::Create(Context, CurContext, UsingLoc, 
-                                           QualifierLoc, NameInfo);
+                                           QualifierLoc, NameInfo, EllipsisLoc);
     }
     D->setAccess(AS);
     CurContext->addDecl(D);
@@ -9211,6 +9228,19 @@ NamedDecl *Sema::BuildUsingDeclaration(Scope *S, AccessSpecifier AS,
   return UD;
 }
 
+NamedDecl *Sema::BuildUsingPackDecl(NamedDecl *InstantiatedFrom,
+                                    ArrayRef<NamedDecl *> Expansions) {
+  assert(isa<UnresolvedUsingValueDecl>(InstantiatedFrom) ||
+         isa<UnresolvedUsingTypenameDecl>(InstantiatedFrom) ||
+         isa<UsingPackDecl>(InstantiatedFrom));
+
+  auto *UPD =
+      UsingPackDecl::Create(Context, CurContext, InstantiatedFrom, Expansions);
+  UPD->setAccess(InstantiatedFrom->getAccess());
+  CurContext->addDecl(UPD);
+  return UPD;
+}
+
 /// Additional checks for a using declaration referring to a constructor name.
 bool Sema::CheckInheritingConstructorUsingDecl(UsingDecl *UD) {
   assert(!UD->hasTypename() && "expecting a constructor name");
@@ -9264,7 +9294,7 @@ bool Sema::CheckUsingDeclRedeclaration(SourceLocation UsingLoc,
     // scope?
     if (Qual->isDependent() && !HasTypenameKeyword) {
       for (auto *D : Prev) {
-        if (!isa<TypeDecl>(D) && !isa<UsingDecl>(D)) {
+        if (!isa<TypeDecl>(D) && !isa<UsingDecl>(D) && !isa<UsingPackDecl>(D)) {
           bool OldCouldBeEnumerator =
               isa<UnresolvedUsingValueDecl>(D) || isa<EnumConstantDecl>(D);
           Diag(NameLoc,
diff --git a/lib/Sema/SemaExprCXX.cpp b/lib/Sema/SemaExprCXX.cpp
index 74beeac724..5c3900adbd 100644
--- a/lib/Sema/SemaExprCXX.cpp
+++ b/lib/Sema/SemaExprCXX.cpp
@@ -7462,17 +7462,11 @@ Sema::CheckMicrosoftIfExistsSymbol(Scope *S, SourceLocation KeywordLoc,
                                    UnqualifiedId &Name) {
   DeclarationNameInfo TargetNameInfo = GetNameFromUnqualifiedId(Name);
 
-  // Check for unexpanded parameter packs.
-  SmallVector<UnexpandedParameterPack, 4> Unexpanded;
-  collectUnexpandedParameterPacks(SS, Unexpanded);
-  collectUnexpandedParameterPacks(TargetNameInfo, Unexpanded);
-  if (!Unexpanded.empty()) {
-    DiagnoseUnexpandedParameterPacks(KeywordLoc,
-                                     IsIfExists? UPPC_IfExists
-                                               : UPPC_IfNotExists,
-                                     Unexpanded);
+  // Check for an unexpanded parameter pack.
+  auto UPPC = IsIfExists ? UPPC_IfExists : UPPC_IfNotExists;
+  if (DiagnoseUnexpandedParameterPack(SS, UPPC) ||
+      DiagnoseUnexpandedParameterPack(TargetNameInfo, UPPC))
     return IER_Error;
-  }
 
   return CheckMicrosoftIfExistsSymbol(S, SS, TargetNameInfo);
 }
diff --git a/lib/Sema/SemaOverload.cpp b/lib/Sema/SemaOverload.cpp
index d49142b8d8..2129729dab 100644
--- a/lib/Sema/SemaOverload.cpp
+++ b/lib/Sema/SemaOverload.cpp
@@ -981,7 +981,7 @@ Sema::CheckOverload(Scope *S, FunctionDecl *New, const LookupResult &Old,
         Match = *I;
         return Ovl_Match;
       }
-    } else if (isa<UsingDecl>(OldD)) {
+    } else if (isa<UsingDecl>(OldD) || isa<UsingPackDecl>(OldD)) {
       // We can overload with these, which can show up when doing
       // redeclaration checks for UsingDecls.
       assert(Old.getLookupKind() == LookupUsingDeclName);
@@ -11420,6 +11420,12 @@ BuildRecoveryCallExpr(Sema &SemaRef, Scope *S, Expr *Fn,
 
   assert(!R.empty() && "lookup results empty despite recovery");
 
+  // If recovery created an ambiguity, just bail out.
+  if (R.isAmbiguous()) {
+    R.suppressDiagnostics();
+    return ExprError();
+  }
+
   // Build an implicit member call if appropriate.  Just drop the
   // casts and such from the call, we don't really care.
   ExprResult NewFn = ExprError();
diff --git a/lib/Sema/SemaTemplateInstantiateDecl.cpp b/lib/Sema/SemaTemplateInstantiateDecl.cpp
index 0956a1cc50..dbc322ebfd 100644
--- a/lib/Sema/SemaTemplateInstantiateDecl.cpp
+++ b/lib/Sema/SemaTemplateInstantiateDecl.cpp
@@ -2495,8 +2495,73 @@ Decl *TemplateDeclInstantiator::VisitConstructorUsingShadowDecl(
   return nullptr;
 }
 
-Decl * TemplateDeclInstantiator
-    ::VisitUnresolvedUsingTypenameDecl(UnresolvedUsingTypenameDecl *D) {
+template <typename T>
+Decl *TemplateDeclInstantiator::instantiateUnresolvedUsingDecl(
+    T *D, bool InstantiatingPackElement) {
+  // If this is a pack expansion, expand it now.
+  if (D->isPackExpansion() && !InstantiatingPackElement) {
+    SmallVector<UnexpandedParameterPack, 2> Unexpanded;
+    SemaRef.collectUnexpandedParameterPacks(D->getQualifierLoc(), Unexpanded);
+    SemaRef.collectUnexpandedParameterPacks(D->getNameInfo(), Unexpanded);
+
+    // Determine whether the set of unexpanded parameter packs can and should
+    // be expanded.
+    bool Expand = true;
+    bool RetainExpansion = false;
+    Optional<unsigned> NumExpansions;
+    if (SemaRef.CheckParameterPacksForExpansion(
+          D->getEllipsisLoc(), D->getSourceRange(), Unexpanded, TemplateArgs,
+            Expand, RetainExpansion, NumExpansions))
+      return nullptr;
+
+    // This declaration cannot appear within a function template signature,
+    // so we can't have a partial argument list for a parameter pack.
+    assert(!RetainExpansion &&
+           "should never need to retain an expansion for UsingPackDecl");
+
+    if (!Expand) {
+      // We cannot fully expand the pack expansion now, so substitute into the
+      // pattern and create a new pack expansion.
+      Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(SemaRef, -1);
+      return instantiateUnresolvedUsingDecl(D, true);
+    }
+
+    // Within a function, we don't have any normal way to check for conflicts
+    // between shadow declarations from different using declarations in the
+    // same pack expansion, but this is always ill-formed because all expansions
+    // must produce (conflicting) enumerators.
+    //
+    // Sadly we can't just reject this in the template definition because it
+    // could be valid if the pack is empty or has exactly one expansion.
+    if (D->getDeclContext()->isFunctionOrMethod() && *NumExpansions > 1) {
+      SemaRef.Diag(D->getEllipsisLoc(),
+                   diag::err_using_decl_redeclaration_expansion);
+      return nullptr;
+    }
+
+    // Instantiate the slices of this pack and build a UsingPackDecl.
+    SmallVector<NamedDecl*, 8> Expansions;
+    for (unsigned I = 0; I != *NumExpansions; ++I) {
+      Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(SemaRef, I);
+      Decl *Slice = instantiateUnresolvedUsingDecl(D, true);
+      if (!Slice)
+        return nullptr;
+      // Note that we can still get unresolved using declarations here, if we
+      // had arguments for all packs but the pattern also contained other
+      // template arguments (this only happens during partial substitution, eg
+      // into the body of a generic lambda in a function template).
+      Expansions.push_back(cast<NamedDecl>(Slice));
+    }
+
+    auto *NewD = SemaRef.BuildUsingPackDecl(D, Expansions);
+    if (isDeclWithinFunction(D))
+      SemaRef.CurrentInstantiationScope->InstantiatedLocal(D, NewD);
+    return NewD;
+  }
+
+  UnresolvedUsingTypenameDecl *TD = dyn_cast<UnresolvedUsingTypenameDecl>(D);
+  SourceLocation TypenameLoc = TD ? TD->getTypenameLoc() : SourceLocation();
+
   NestedNameSpecifierLoc QualifierLoc
     = SemaRef.SubstNestedNameSpecifierLoc(D->getQualifierLoc(),
                                           TemplateArgs);
@@ -2506,44 +2571,51 @@ Decl * TemplateDeclInstantiator
   CXXScopeSpec SS;
   SS.Adopt(QualifierLoc);
 
-  // Since NameInfo refers to a typename, it cannot be a C++ special name.
-  // Hence, no transformation is required for it.
-  DeclarationNameInfo NameInfo(D->getDeclName(), D->getLocation());
-  NamedDecl *UD =
-    SemaRef.BuildUsingDeclaration(/*Scope*/ nullptr, D->getAccess(),
-                                  D->getUsingLoc(), SS, NameInfo, nullptr,
-                                  /*instantiation*/ true,
-                                  /*typename*/ true, D->getTypenameLoc());
-  if (UD)
-    SemaRef.Context.setInstantiatedFromUsingDecl(UD, D);
-
-  return UD;
-}
-
-Decl * TemplateDeclInstantiator
-    ::VisitUnresolvedUsingValueDecl(UnresolvedUsingValueDecl *D) {
-  NestedNameSpecifierLoc QualifierLoc
-      = SemaRef.SubstNestedNameSpecifierLoc(D->getQualifierLoc(), TemplateArgs);
-  if (!QualifierLoc)
-    return nullptr;
-
-  CXXScopeSpec SS;
-  SS.Adopt(QualifierLoc);
-
   DeclarationNameInfo NameInfo
     = SemaRef.SubstDeclarationNameInfo(D->getNameInfo(), TemplateArgs);
 
-  NamedDecl *UD =
-    SemaRef.BuildUsingDeclaration(/*Scope*/ nullptr, D->getAccess(),
-                                  D->getUsingLoc(), SS, NameInfo, nullptr,
-                                  /*instantiation*/ true,
-                                  /*typename*/ false, SourceLocation());
+  // Produce a pack expansion only if we're not instantiating a particular
+  // slice of a pack expansion.
+  bool InstantiatingSlice = D->getEllipsisLoc().isValid() &&
+                            SemaRef.ArgumentPackSubstitutionIndex != -1;
+  SourceLocation EllipsisLoc =
+      InstantiatingSlice ? SourceLocation() : D->getEllipsisLoc();
+
+  NamedDecl *UD = SemaRef.BuildUsingDeclaration(
+      /*Scope*/ nullptr, D->getAccess(), D->getUsingLoc(),
+      /*HasTypename*/ TD, TypenameLoc, SS, NameInfo, EllipsisLoc, nullptr,
+      /*IsInstantiation*/ true);
   if (UD)
     SemaRef.Context.setInstantiatedFromUsingDecl(UD, D);
 
   return UD;
 }
 
+Decl *TemplateDeclInstantiator::VisitUnresolvedUsingTypenameDecl(
+    UnresolvedUsingTypenameDecl *D) {
+  return instantiateUnresolvedUsingDecl(D);
+}
+
+Decl *TemplateDeclInstantiator::VisitUnresolvedUsingValueDecl(
+    UnresolvedUsingValueDecl *D) {
+  return instantiateUnresolvedUsingDecl(D);
+}
+
+Decl *TemplateDeclInstantiator::VisitUsingPackDecl(UsingPackDecl *D) {
+  SmallVector<NamedDecl*, 8> Expansions;
+  for (auto *UD : D->expansions()) {
+    if (auto *NewUD =
+            SemaRef.FindInstantiatedDecl(D->getLocation(), UD, TemplateArgs))
+      Expansions.push_back(cast<NamedDecl>(NewUD));
+    else
+      return nullptr;
+  }
+
+  auto *NewD = SemaRef.BuildUsingPackDecl(D, Expansions);
+  if (isDeclWithinFunction(D))
+    SemaRef.CurrentInstantiationScope->InstantiatedLocal(D, NewD);
+  return NewD;
+}
 
 Decl *TemplateDeclInstantiator::VisitClassScopeFunctionSpecializationDecl(
                                      ClassScopeFunctionSpecializationDecl *Decl) {
@@ -4513,22 +4585,36 @@ static bool isInstantiationOf(UsingShadowDecl *Pattern,
                             Pattern);
 }
 
-static bool isInstantiationOf(UsingDecl *Pattern,
-                              UsingDecl *Instance,
+static bool isInstantiationOf(UsingDecl *Pattern, UsingDecl *Instance,
                               ASTContext &C) {
   return declaresSameEntity(C.getInstantiatedFromUsingDecl(Instance), Pattern);
 }
 
-static bool isInstantiationOf(UnresolvedUsingValueDecl *Pattern,
-                              NamedDecl *Instance,
-                              ASTContext &C) {
-  return declaresSameEntity(C.getInstantiatedFromUsingDecl(Instance), Pattern);
-}
-
-static bool isInstantiationOf(UnresolvedUsingTypenameDecl *Pattern,
-                              NamedDecl *Instance,
-                              ASTContext &C) {
-  return declaresSameEntity(C.getInstantiatedFromUsingDecl(Instance), Pattern);
+template<typename T>
+static bool isInstantiationOfUnresolvedUsingDecl(T *Pattern, Decl *Other,
+                                                 ASTContext &Ctx) {
+  // An unresolved using declaration can instantiate to an unresolved using
+  // declaration, or to a using declaration or a using declaration pack.
+  //
+  // Multiple declarations can claim to be instantiated from an unresolved
+  // using declaration if it's a pack expansion. We want the UsingPackDecl
+  // in that case, not the individual UsingDecls within the pack.
+  bool OtherIsPackExpansion;
+  NamedDecl *OtherFrom;
+  if (auto *OtherUUD = dyn_cast<T>(Other)) {
+    OtherIsPackExpansion = OtherUUD->isPackExpansion();
+    OtherFrom = Ctx.getInstantiatedFromUsingDecl(OtherUUD);
+  } else if (auto *OtherUPD = dyn_cast<UsingPackDecl>(Other)) {
+    OtherIsPackExpansion = true;
+    OtherFrom = OtherUPD->getInstantiatedFromUsingDecl();
+  } else if (auto *OtherUD = dyn_cast<UsingDecl>(Other)) {
+    OtherIsPackExpansion = false;
+    OtherFrom = Ctx.getInstantiatedFromUsingDecl(OtherUD);
+  } else {
+    return false;
+  }
+  return Pattern->isPackExpansion() == OtherIsPackExpansion &&
+         declaresSameEntity(OtherFrom, Pattern);
 }
 
 static bool isInstantiationOfStaticDataMember(VarDecl *Pattern,
@@ -4549,21 +4635,14 @@ static bool isInstantiationOfStaticDataMember(VarDecl *Pattern,
 // Other is the prospective instantiation
 // D is the prospective pattern
 static bool isInstantiationOf(ASTContext &Ctx, NamedDecl *D, Decl *Other) {
-  if (D->getKind() != Other->getKind()) {
-    if (auto *UUD = dyn_cast<UnresolvedUsingTypenameDecl>(D)) {
-      if (UsingDecl *UD = dyn_cast<UsingDecl>(Other)) {
-        return isInstantiationOf(UUD, UD, Ctx);
-      }
-    }
+  if (auto *UUD = dyn_cast<UnresolvedUsingTypenameDecl>(D))
+    return isInstantiationOfUnresolvedUsingDecl(UUD, Other, Ctx);
 
-    if (auto *UUD = dyn_cast<UnresolvedUsingValueDecl>(D)) {
-      if (UsingDecl *UD = dyn_cast<UsingDecl>(Other)) {
-        return isInstantiationOf(UUD, UD, Ctx);
-      }
-    }
+  if (auto *UUD = dyn_cast<UnresolvedUsingValueDecl>(D))
+    return isInstantiationOfUnresolvedUsingDecl(UUD, Other, Ctx);
 
+  if (D->getKind() != Other->getKind())
     return false;
-  }
 
   if (auto *Record = dyn_cast<CXXRecordDecl>(Other))
     return isInstantiationOf(cast<CXXRecordDecl>(D), Record);
@@ -4600,12 +4679,6 @@ static bool isInstantiationOf(ASTContext &Ctx, NamedDecl *D, Decl *Other) {
   if (auto *Using = dyn_cast<UsingDecl>(Other))
     return isInstantiationOf(cast<UsingDecl>(D), Using, Ctx);
 
-  if (auto *Using = dyn_cast<UnresolvedUsingValueDecl>(Other))
-    return isInstantiationOf(cast<UnresolvedUsingValueDecl>(D), Using, Ctx);
-
-  if (auto *Using = dyn_cast<UnresolvedUsingTypenameDecl>(Other))
-    return isInstantiationOf(cast<UnresolvedUsingTypenameDecl>(D), Using, Ctx);
-
   if (auto *Shadow = dyn_cast<UsingShadowDecl>(Other))
     return isInstantiationOf(cast<UsingShadowDecl>(D), Shadow, Ctx);
 
@@ -4846,6 +4919,8 @@ NamedDecl *Sema::FindInstantiatedDecl(SourceLocation Loc, NamedDecl *D,
     }
 
     NamedDecl *Result = nullptr;
+    // FIXME: If the name is a dependent name, this lookup won't necessarily
+    // find it. Does that ever matter?
     if (D->getDeclName()) {
       DeclContext::lookup_result Found = ParentDC->lookup(D->getDeclName());
       Result = findInstantiationOf(Context, D, Found.begin(), Found.end());
diff --git a/lib/Sema/SemaTemplateVariadic.cpp b/lib/Sema/SemaTemplateVariadic.cpp
index c8bc2c3880..54556b505e 100644
--- a/lib/Sema/SemaTemplateVariadic.cpp
+++ b/lib/Sema/SemaTemplateVariadic.cpp
@@ -390,21 +390,18 @@ void Sema::collectUnexpandedParameterPacks(QualType T,
 void Sema::collectUnexpandedParameterPacks(TypeLoc TL,
                    SmallVectorImpl<UnexpandedParameterPack> &Unexpanded) {
   CollectUnexpandedParameterPacksVisitor(Unexpanded).TraverseTypeLoc(TL);  
-}  
-
-void Sema::collectUnexpandedParameterPacks(CXXScopeSpec &SS,
-                                           SmallVectorImpl<UnexpandedParameterPack> &Unexpanded) {
-  NestedNameSpecifier *Qualifier = SS.getScopeRep();
-  if (!Qualifier)
-    return;
-  
-  NestedNameSpecifierLoc QualifierLoc(Qualifier, SS.location_data());
-  CollectUnexpandedParameterPacksVisitor(Unexpanded)
-    .TraverseNestedNameSpecifierLoc(QualifierLoc);
 }
 
-void Sema::collectUnexpandedParameterPacks(const DeclarationNameInfo &NameInfo,
-                         SmallVectorImpl<UnexpandedParameterPack> &Unexpanded) {
+void Sema::collectUnexpandedParameterPacks(
+    NestedNameSpecifierLoc NNS,
+    SmallVectorImpl<UnexpandedParameterPack> &Unexpanded) {
+  CollectUnexpandedParameterPacksVisitor(Unexpanded)
+      .TraverseNestedNameSpecifierLoc(NNS);
+}
+
+void Sema::collectUnexpandedParameterPacks(
+    const DeclarationNameInfo &NameInfo,
+    SmallVectorImpl<UnexpandedParameterPack> &Unexpanded) {
   CollectUnexpandedParameterPacksVisitor(Unexpanded)
     .TraverseDeclarationNameInfo(NameInfo);
 }
diff --git a/lib/Sema/TreeTransform.h b/lib/Sema/TreeTransform.h
index a76a078fd0..9671b9b35d 100644
--- a/lib/Sema/TreeTransform.h
+++ b/lib/Sema/TreeTransform.h
@@ -457,6 +457,10 @@ public:
     return cast_or_null<NamedDecl>(getDerived().TransformDecl(Loc, D));
   }
 
+  /// Transform the set of declarations in an OverloadExpr.
+  bool TransformOverloadExprDecls(OverloadExpr *Old, bool RequiresADL,
+                                  LookupResult &R);
+
   /// \brief Transform the given nested-name-specifier with source-location
   /// information.
   ///
@@ -821,7 +825,7 @@ public:
 
   /// \brief Rebuild an unresolved typename type, given the decl that
   /// the UnresolvedUsingTypenameDecl was transformed to.
-  QualType RebuildUnresolvedUsingType(Decl *D);
+  QualType RebuildUnresolvedUsingType(SourceLocation NameLoc, Decl *D);
 
   /// \brief Build a new typedef type.
   QualType RebuildTypedefType(TypedefNameDecl *Typedef) {
@@ -5161,7 +5165,7 @@ TreeTransform<Derived>::TransformUnresolvedUsingType(TypeLocBuilder &TLB,
 
   QualType Result = TL.getType();
   if (getDerived().AlwaysRebuild() || D != T->getDecl()) {
-    Result = getDerived().RebuildUnresolvedUsingType(D);
+    Result = getDerived().RebuildUnresolvedUsingType(TL.getNameLoc(), D);
     if (Result.isNull())
       return QualType();
   }
@@ -9794,6 +9798,62 @@ TreeTransform<Derived>::TransformCXXPseudoDestructorExpr(
                                                      Destroyed);
 }
 
+template <typename Derived>
+bool TreeTransform<Derived>::TransformOverloadExprDecls(OverloadExpr *Old,
+                                                        bool RequiresADL,
+                                                        LookupResult &R) {
+  // Transform all the decls.
+  bool AllEmptyPacks = true;
+  for (auto *OldD : Old->decls()) {
+    Decl *InstD = getDerived().TransformDecl(Old->getNameLoc(), OldD);
+    if (!InstD) {
+      // Silently ignore these if a UsingShadowDecl instantiated to nothing.
+      // This can happen because of dependent hiding.
+      if (isa<UsingShadowDecl>(OldD))
+        continue;
+      else {
+        R.clear();
+        return true;
+      }
+    }
+
+    // Expand using pack declarations.
+    NamedDecl *SingleDecl = cast<NamedDecl>(InstD);
+    ArrayRef<NamedDecl*> Decls = SingleDecl;
+    if (auto *UPD = dyn_cast<UsingPackDecl>(InstD))
+      Decls = UPD->expansions();
+
+    // Expand using declarations.
+    for (auto *D : Decls) {
+      if (auto *UD = dyn_cast<UsingDecl>(D)) {
+        for (auto *SD : UD->shadows())
+          R.addDecl(SD);
+      } else {
+        R.addDecl(D);
+      }
+    }
+
+    AllEmptyPacks &= Decls.empty();
+  };
+
+  // C++ [temp.res]/8.4.2:
+  //   The program is ill-formed, no diagnostic required, if [...] lookup for
+  //   a name in the template definition found a using-declaration, but the
+  //   lookup in the corresponding scope in the instantiation odoes not find
+  //   any declarations because the using-declaration was a pack expansion and
+  //   the corresponding pack is empty
+  if (AllEmptyPacks && !RequiresADL) {
+    getSema().Diag(Old->getNameLoc(), diag::err_using_pack_expansion_empty)
+        << isa<UnresolvedMemberExpr>(Old) << Old->getNameInfo().getName();
+    return true;
+  }
+
+  // Resolve a kind, but don't do any further analysis.  If it's
+  // ambiguous, the callee needs to deal with it.
+  R.resolveKind();
+  return false;
+}
+
 template<typename Derived>
 ExprResult
 TreeTransform<Derived>::TransformUnresolvedLookupExpr(
@@ -9801,37 +9861,9 @@ TreeTransform<Derived>::TransformUnresolvedLookupExpr(
   LookupResult R(SemaRef, Old->getName(), Old->getNameLoc(),
                  Sema::LookupOrdinaryName);
 
-  // Transform all the decls.
-  for (UnresolvedLookupExpr::decls_iterator I = Old->decls_begin(),
-         E = Old->decls_end(); I != E; ++I) {
-    NamedDecl *InstD = static_cast<NamedDecl*>(
-                                 getDerived().TransformDecl(Old->getNameLoc(),
-                                                            *I));
-    if (!InstD) {
-      // Silently ignore these if a UsingShadowDecl instantiated to nothing.
-      // This can happen because of dependent hiding.
-      if (isa<UsingShadowDecl>(*I))
-        continue;
-      else {
-        R.clear();
-        return ExprError();
-      }
-    }
-
-    // Expand using declarations.
-    if (isa<UsingDecl>(InstD)) {
-      UsingDecl *UD = cast<UsingDecl>(InstD);
-      for (auto *I : UD->shadows())
-        R.addDecl(I);
-      continue;
-    }
-
-    R.addDecl(InstD);
-  }
-
-  // Resolve a kind, but don't do any further analysis.  If it's
-  // ambiguous, the callee needs to deal with it.
-  R.resolveKind();
+  // Transform the declaration set.
+  if (TransformOverloadExprDecls(Old, Old->requiresADL(), R))
+    return ExprError();
 
   // Rebuild the nested-name qualifier, if present.
   CXXScopeSpec SS;
@@ -10699,35 +10731,9 @@ TreeTransform<Derived>::TransformUnresolvedMemberExpr(UnresolvedMemberExpr *Old)
   LookupResult R(SemaRef, Old->getMemberNameInfo(),
                  Sema::LookupOrdinaryName);
 
-  // Transform all the decls.
-  for (UnresolvedMemberExpr::decls_iterator I = Old->decls_begin(),
-         E = Old->decls_end(); I != E; ++I) {
-    NamedDecl *InstD = static_cast<NamedDecl*>(
-                                getDerived().TransformDecl(Old->getMemberLoc(),
-                                                           *I));
-    if (!InstD) {
-      // Silently ignore these if a UsingShadowDecl instantiated to nothing.
-      // This can happen because of dependent hiding.
-      if (isa<UsingShadowDecl>(*I))
-        continue;
-      else {
-        R.clear();
-        return ExprError();
-      }
-    }
-
-    // Expand using declarations.
-    if (isa<UsingDecl>(InstD)) {
-      UsingDecl *UD = cast<UsingDecl>(InstD);
-      for (auto *I : UD->shadows())
-        R.addDecl(I);
-      continue;
-    }
-
-    R.addDecl(InstD);
-  }
-
-  R.resolveKind();
+  // Transform the declaration set.
+  if (TransformOverloadExprDecls(Old, /*RequiresADL*/false, R))
+    return ExprError();
 
   // Determine the naming class.
   if (Old->getNamingClass()) {
@@ -11842,21 +11848,48 @@ QualType TreeTransform<Derived>::RebuildFunctionNoProtoType(QualType T) {
 }
 
 template<typename Derived>
-QualType TreeTransform<Derived>::RebuildUnresolvedUsingType(Decl *D) {
+QualType TreeTransform<Derived>::RebuildUnresolvedUsingType(SourceLocation Loc,
+                                                            Decl *D) {
   assert(D && "no decl found");
   if (D->isInvalidDecl()) return QualType();
 
   // FIXME: Doesn't account for ObjCInterfaceDecl!
   TypeDecl *Ty;
-  if (isa<UsingDecl>(D)) {
-    UsingDecl *Using = cast<UsingDecl>(D);
+  if (auto *UPD = dyn_cast<UsingPackDecl>(D)) {
+    // A valid resolved using typename pack expansion decl can have multiple
+    // UsingDecls, but they must each have exactly one type, and it must be
+    // the same type in every case. But we must have at least one expansion!
+    if (UPD->expansions().empty()) {
+      getSema().Diag(Loc, diag::err_using_pack_expansion_empty)
+          << UPD->isCXXClassMember() << UPD;
+      return QualType();
+    }
+
+    // We might still have some unresolved types. Try to pick a resolved type
+    // if we can. The final instantiation will check that the remaining
+    // unresolved types instantiate to the type we pick.
+    QualType FallbackT;
+    QualType T;
+    for (auto *E : UPD->expansions()) {
+      QualType ThisT = RebuildUnresolvedUsingType(Loc, E);
+      if (ThisT.isNull())
+        continue;
+      else if (ThisT->getAs<UnresolvedUsingType>())
+        FallbackT = ThisT;
+      else if (T.isNull())
+        T = ThisT;
+      else
+        assert(getSema().Context.hasSameType(ThisT, T) &&
+               "mismatched resolved types in using pack expansion");
+    }
+    return T.isNull() ? FallbackT : T;
+  } else if (auto *Using = dyn_cast<UsingDecl>(D)) {
     assert(Using->hasTypename() &&
            "UnresolvedUsingTypenameDecl transformed to non-typename using");
 
     // A valid resolved using typename decl points to exactly one type decl.
     assert(++Using->shadow_begin() == Using->shadow_end());
     Ty = cast<TypeDecl>((*Using->shadow_begin())->getTargetDecl());
-
   } else {
     assert(isa<UnresolvedUsingTypenameDecl>(D) &&
            "UnresolvedUsingTypenameDecl transformed to non-using decl");
diff --git a/lib/Serialization/ASTCommon.cpp b/lib/Serialization/ASTCommon.cpp
index 79ccffc5ab..ecd249cc50 100644
--- a/lib/Serialization/ASTCommon.cpp
+++ b/lib/Serialization/ASTCommon.cpp
@@ -285,6 +285,7 @@ bool serialization::isRedeclarableDeclKind(unsigned Kind) {
   case Decl::NonTypeTemplateParm:
   case Decl::TemplateTemplateParm:
   case Decl::Using:
+  case Decl::UsingPack:
   case Decl::ObjCMethod:
   case Decl::ObjCCategory:
   case Decl::ObjCCategoryImpl:
diff --git a/lib/Serialization/ASTReaderDecl.cpp b/lib/Serialization/ASTReaderDecl.cpp
index 913a1419b3..dc29a61c0a 100644
--- a/lib/Serialization/ASTReaderDecl.cpp
+++ b/lib/Serialization/ASTReaderDecl.cpp
@@ -322,6 +322,7 @@ namespace clang {
     void VisitTemplateTemplateParmDecl(TemplateTemplateParmDecl *D);
     void VisitTypeAliasTemplateDecl(TypeAliasTemplateDecl *D);
     void VisitUsingDecl(UsingDecl *D);
+    void VisitUsingPackDecl(UsingPackDecl *D);
     void VisitUsingShadowDecl(UsingShadowDecl *D);
     void VisitConstructorUsingShadowDecl(ConstructorUsingShadowDecl *D);
     void VisitLinkageSpecDecl(LinkageSpecDecl *D);
@@ -1419,6 +1420,15 @@ void ASTDeclReader::VisitUsingDecl(UsingDecl *D) {
   mergeMergeable(D);
 }
 
+void ASTDeclReader::VisitUsingPackDecl(UsingPackDecl *D) {
+  VisitNamedDecl(D);
+  D->InstantiatedFrom = ReadDeclAs<NamedDecl>();
+  NamedDecl **Expansions = D->getTrailingObjects<NamedDecl*>();
+  for (unsigned I = 0; I != D->NumExpansions; ++I)
+    Expansions[I] = ReadDeclAs<NamedDecl>();
+  mergeMergeable(D);
+}
+
 void ASTDeclReader::VisitUsingShadowDecl(UsingShadowDecl *D) {
   RedeclarableResult Redecl = VisitRedeclarable(D);
   VisitNamedDecl(D);
@@ -1452,6 +1462,7 @@ void ASTDeclReader::VisitUnresolvedUsingValueDecl(UnresolvedUsingValueDecl *D) {
   D->setUsingLoc(ReadSourceLocation());
   D->QualifierLoc = Record.ReadNestedNameSpecifierLoc(Idx);
   ReadDeclarationNameLoc(D->DNLoc, D->getDeclName());
+  D->EllipsisLoc = ReadSourceLocation();
   mergeMergeable(D);
 }
 
@@ -1460,6 +1471,7 @@ void ASTDeclReader::VisitUnresolvedUsingTypenameDecl(
   VisitTypeDecl(D);
   D->TypenameLocation = ReadSourceLocation();
   D->QualifierLoc = Record.ReadNestedNameSpecifierLoc(Idx);
+  D->EllipsisLoc = ReadSourceLocation();
   mergeMergeable(D);
 }
 
@@ -3297,6 +3309,9 @@ Decl *ASTReader::ReadDeclRecord(DeclID ID) {
   case DECL_USING:
     D = UsingDecl::CreateDeserialized(Context, ID);
     break;
+  case DECL_USING_PACK:
+    D = UsingPackDecl::CreateDeserialized(Context, ID, Record[Idx++]);
+    break;
   case DECL_USING_SHADOW:
     D = UsingShadowDecl::CreateDeserialized(Context, ID);
     break;
diff --git a/lib/Serialization/ASTWriterDecl.cpp b/lib/Serialization/ASTWriterDecl.cpp
index 21468619db..ee220f00a8 100644
--- a/lib/Serialization/ASTWriterDecl.cpp
+++ b/lib/Serialization/ASTWriterDecl.cpp
@@ -107,6 +107,7 @@ namespace clang {
     void VisitTemplateTemplateParmDecl(TemplateTemplateParmDecl *D);
     void VisitTypeAliasTemplateDecl(TypeAliasTemplateDecl *D);
     void VisitUsingDecl(UsingDecl *D);
+    void VisitUsingPackDecl(UsingPackDecl *D);
     void VisitUsingShadowDecl(UsingShadowDecl *D);
     void VisitConstructorUsingShadowDecl(ConstructorUsingShadowDecl *D);
     void VisitLinkageSpecDecl(LinkageSpecDecl *D);
@@ -1142,6 +1143,15 @@ void ASTDeclWriter::VisitUsingDecl(UsingDecl *D) {
   Code = serialization::DECL_USING;
 }
 
+void ASTDeclWriter::VisitUsingPackDecl(UsingPackDecl *D) {
+  Record.push_back(D->NumExpansions);
+  VisitNamedDecl(D);
+  Record.AddDeclRef(D->getInstantiatedFromUsingDecl());
+  for (auto *E : D->expansions())
+    Record.AddDeclRef(E);
+  Code = serialization::DECL_USING_PACK;
+}
+
 void ASTDeclWriter::VisitUsingShadowDecl(UsingShadowDecl *D) {
   VisitRedeclarable(D);
   VisitNamedDecl(D);
@@ -1175,6 +1185,7 @@ void ASTDeclWriter::VisitUnresolvedUsingValueDecl(UnresolvedUsingValueDecl *D) {
   Record.AddSourceLocation(D->getUsingLoc());
   Record.AddNestedNameSpecifierLoc(D->getQualifierLoc());
   Record.AddDeclarationNameLoc(D->DNLoc, D->getDeclName());
+  Record.AddSourceLocation(D->getEllipsisLoc());
   Code = serialization::DECL_UNRESOLVED_USING_VALUE;
 }
 
@@ -1183,6 +1194,7 @@ void ASTDeclWriter::VisitUnresolvedUsingTypenameDecl(
   VisitTypeDecl(D);
   Record.AddSourceLocation(D->getTypenameLoc());
   Record.AddNestedNameSpecifierLoc(D->getQualifierLoc());
+  Record.AddSourceLocation(D->getEllipsisLoc());
   Code = serialization::DECL_UNRESOLVED_USING_TYPENAME;
 }
 
diff --git a/test/PCH/cxx1z-using-declaration.cpp b/test/PCH/cxx1z-using-declaration.cpp
new file mode 100644
index 0000000000..a185ff1740
--- /dev/null
+++ b/test/PCH/cxx1z-using-declaration.cpp
@@ -0,0 +1,35 @@
+// No PCH:
+// RUN: %clang_cc1 -pedantic -std=c++1z -include %s -verify %s
+//
+// With PCH:
+// RUN: %clang_cc1 -pedantic -std=c++1z -emit-pch %s -o %t
+// RUN: %clang_cc1 -pedantic -std=c++1z -include-pch %t -verify %s
+
+#ifndef HEADER
+#define HEADER
+
+template<typename ...T> struct A : T... {
+  using T::f ...;
+  template<typename ...U> void g(U ...u) { f(u...); }
+};
+
+struct X { void f(); };
+struct Y { void f(int); };
+struct Z { void f(int, int); };
+
+inline A<X, Y, Z> a;
+
+#else
+
+void test() {
+  a.g();
+  a.g(0);
+  a.g(0, 0);
+  // expected-error@13 {{no match}}
+  // expected-note@16 {{candidate}}
+  // expected-note@17 {{candidate}}
+  // expected-note@18 {{candidate}}
+  a.g(0, 0, 0); // expected-note {{instantiation of}}
+}
+
+#endif
diff --git a/test/Parser/cxx1z-using-declaration.cpp b/test/Parser/cxx1z-using-declaration.cpp
index dab1ca82c2..0be81677d9 100644
--- a/test/Parser/cxx1z-using-declaration.cpp
+++ b/test/Parser/cxx1z-using-declaration.cpp
@@ -10,10 +10,10 @@ namespace B {
 }
 
 struct X {
-  int x1, x2, y, z; // expected-note {{conflicting}}
+  int x1, x2, y, z; // expected-note 2{{conflicting}}
 };
 struct Y {
-  int x1, x2, y, z; // expected-note {{target}}
+  int x1, x2, y, z; // expected-note 2{{target}}
 };
 struct Z : X, Y {
   using X::x1,
@@ -28,3 +28,8 @@ int X::*px1 = &Z::x1;
 int X::*px2 = &Z::x2;
 int Y::*py = &Z::y;
 int X::*pz = &Z::z;
+
+template<typename ...T> struct Q : T... {
+  using T::z...; // expected-error {{conflicts}}
+};
+Q<X,Y> q; // expected-note {{instantiation of}}
diff --git a/test/SemaTemplate/cxx1z-using-declaration.cpp b/test/SemaTemplate/cxx1z-using-declaration.cpp
new file mode 100644
index 0000000000..7bef36db1f
--- /dev/null
+++ b/test/SemaTemplate/cxx1z-using-declaration.cpp
@@ -0,0 +1,230 @@
+// RUN: %clang_cc1 -std=c++1z -verify %s
+
+// Test that we cope with failure to expand a pack.
+template<typename ...T> struct Unexpanded : T... {
+  using T::f; // expected-error {{unexpanded}}
+  using typename T::type; // expected-error {{unexpanded}}
+  template<typename ...U> void g(U ...u) { f(u...); } // expected-error {{undeclared identifier 'f'}}
+  void h() {
+    Unexpanded<type...> *p; // expected-error {{undeclared identifier 'type'}}
+  }
+};
+void test_Unexpanded() {
+  struct A { void f(); }; // expected-note {{must qualify}}
+  struct B { void f(int); }; // expected-note {{must qualify}}
+  Unexpanded<A, B>().g(0); // expected-note {{instantiation of}}
+}
+
+// Test using non-type members from pack of base classes.
+template<typename ...T> struct A : T... { // expected-note 2{{candidate}}
+  using T::T ...; // expected-note 6{{inherited here}}
+  using T::operator() ...;
+  using T::operator T* ...;
+  using T::h ...;
+
+  void f(int n) { h(n); } // expected-error {{ambiguous}}
+  void f(int n, int m) { h(n, m); } // expected-error {{member using declaration 'h' instantiates to an empty pack}}
+  void g(int n) { (*this)(n); } // expected-error {{ambiguous}}
+  void g(int n, int m) { (*this)(n, m); } // expected-error {{does not provide a call operator}}
+};
+
+namespace test_A {
+  struct X { // expected-note 2{{candidate}}
+    X();
+    X(int); // expected-note {{candidate}}
+    void operator()(int); // expected-note 2{{candidate}}
+    operator X *();
+    void h(int); // expected-note {{candidate}}
+  };
+  struct Y {
+    Y();
+    Y(int, int);
+    void operator()(int, int);
+    operator Y *();
+    void h(int, int); // expected-note {{not viable}}
+  };
+  struct Z { // expected-note 2{{candidate}}
+    Z();
+    Z(int); // expected-note {{candidate}}
+    void operator()(int); // expected-note 2{{candidate}}
+    operator Z *();
+    void h(int); // expected-note {{candidate}}
+  };
+
+  void f() {
+    A<> a;
+    a.f(0, 0); // expected-note {{instantiation of}}
+    a.g(0, 0); // expected-note {{instantiation of}}
+
+    A<X, Y> axy(0);
+    A<X, Y>(0, 0);
+    axy.f(0);
+    axy.f(0, 0);
+    axy.g(0);
+    axy.g(0, 0);
+    axy(0);
+    axy(0, 0);
+
+    A<X, Y, Z>(0); // expected-error {{ambiguous}}
+    A<X, Y, Z> axyz(0, 0);
+    axyz.f(0); // expected-note {{instantiation of}}
+    axyz.f(0, 0);
+    axyz.g(0); // expected-note {{instantiation of}}
+    axyz.g(0, 0);
+    axyz(0); // expected-error {{ambiguous}}
+    axyz(0, 0);
+
+    X *x;
+    x = a; // expected-error {{incompatible}}
+    x = axy;
+    x = axyz;
+    x = a.operator X*(); // expected-error {{no member}}
+    x = axy.operator X*();
+    x = axyz.operator X*();
+
+    Z *z;
+    z = axyz;
+    z = axyz.operator Z*();
+  }
+}
+
+// Test using pack of non-type members from single base class.
+template<typename X, typename Y, typename ...T> struct B : X, Y {
+  using X::operator T* ...;
+};
+
+namespace test_B {
+  struct X { operator int*(); operator float*(); operator char*(); }; // expected-note {{candidate}}
+  struct Y { operator int*(); operator float*(); operator char*(); }; // expected-note {{candidate}}
+  B<X, Y, int, float> bif;
+  int *pi = bif;
+  float *pf = bif;
+  char *pc = bif; // expected-error {{ambiguous}}
+}
+
+// Test using type member from pack of base classes.
+template<typename ...T> struct C : T... {
+  using typename T::type ...; // expected-error {{target of using declaration conflicts}}
+  void f() { type value; } // expected-error {{member using declaration 'type' instantiates to an empty pack}}
+};
+
+namespace test_C {
+  struct X { typedef int type; };
+  struct Y { typedef int type; }; // expected-note {{conflicting}}
+  struct Z { typedef float type; }; // expected-note {{target}}
+
+  void f() {
+    C<> c;
+    c.f(); // expected-note {{instantiation of}}
+
+    C<X, Y> cxy;
+    cxy.f();
+
+    C<X, Y, Z> cxyz; // expected-note {{instantiation of}}
+    cxyz.f();
+  }
+}
+
+// Test using pack of non-types at block scope.
+template<typename ...T> int fn1() {
+  using T::e ...; // expected-error 2{{class member}} expected-note 2{{instead}}
+  // expected-error@-1 2{{produces multiple values}}
+  return e; // expected-error {{using declaration 'e' instantiates to an empty pack}}
+}
+
+namespace test_fn1 {
+  struct X { static int e; };
+  struct Y { typedef int e; };
+  inline namespace P { enum E { e }; }
+  inline namespace Q { enum F { e }; }
+  void f() {
+    fn1<>(); // expected-note {{instantiation of}}
+    fn1<X>(); // expected-note {{instantiation of}}
+    fn1<Y>(); // expected-note {{instantiation of}}
+    fn1<E>();
+    fn1<E, F>(); // expected-note {{instantiation of}}
+    fn1<E, X>(); // expected-note {{instantiation of}}
+  }
+}
+
+// Test using pack of types at block scope.
+template<typename ...T> void fn2() {
+  // This cannot ever be valid: in order for T::type to be a type, T must be a
+  // class, and a class member cannot be named by a block-scope using declaration.
+  using typename T::type ...; // expected-error {{class member}}
+  type x; // expected-error {{unknown type name 'type'}}
+}
+
+// Test partial substitution into class-scope pack.
+template<typename ...T> auto lambda1() {
+  return [](auto x) {
+    struct A : T::template X<decltype(x)>... { // expected-note 1+{{instantiation of}}
+      using T::template X<decltype(x)>::f ...;
+      using typename T::template X<decltype(x)>::type ...;
+      void g(int n) { f(n); } // expected-error {{empty pack}} expected-error {{expected 2, have 1}} expected-error {{ambiguous}}
+      void h() { type value; } // expected-error {{empty pack}}
+    };
+    return A();
+  };
+}
+
+namespace test_lambda1 {
+  struct A {
+    template<typename> struct X {
+      void f(int); // expected-note {{candidate}}
+      using type = int;
+    };
+  };
+  struct B {
+    template<typename> struct X {
+      void f(int, int); // expected-note {{declared here}} expected-note {{not viable}}
+      using type = int;
+    };
+  };
+  struct C {
+    template<typename> struct X {
+      void f(int); // expected-note {{candidate}}
+      void f(int, int); // expected-note {{not viable}}
+      using type = int;
+    };
+  };
+
+  void f() {
+    lambda1<>() // expected-note 2{{instantiation of}}
+      (0)
+      // FIXME: This is poor error recovery
+      .g(0); // expected-error {{no member named 'g'}}
+    lambda1<A>()
+      (0)
+      .g(0);
+    lambda1<B>()
+      (0) // expected-note {{instantiation of}}
+      .g(0);
+    lambda1<A, B, C>()
+      (0) // expected-note {{instantiation of}}
+      .g(0);
+  }
+}
+
+namespace p0195r2_example {
+  template<typename ...Ts>
+  struct Overloader : Ts... {
+    using Ts::operator() ...;
+  };
+
+  template<typename ...Ts>
+  constexpr auto make_overloader(Ts &&...ts) {
+    return Overloader<Ts...>{static_cast<Ts&&>(ts)...};
+  }
+
+  void test() {
+    auto o = make_overloader(
+      [&](int &r) -> int & { return r; }, // expected-note {{candidate function}}
+      [&](float &r) -> float & { return r; } // expected-note {{candidate function}}
+    );
+    int a; float f; double d;
+    int &ra = o(a);
+    float &rf = o(f);
+    double &rd = o(d); // expected-error {{no matching function}}
+  }
+}
diff --git a/tools/libclang/CIndex.cpp b/tools/libclang/CIndex.cpp
index df048994b2..210e74bf59 100644
--- a/tools/libclang/CIndex.cpp
+++ b/tools/libclang/CIndex.cpp
@@ -5738,6 +5738,7 @@ CXCursor clang_getCursorDefinition(CXCursor C) {
   case Decl::BuiltinTemplate:
   case Decl::PragmaComment:
   case Decl::PragmaDetectMismatch:
+  case Decl::UsingPack:
     return C;
 
   // Declaration kinds that don't make any sense here, but are