Index: clang/include/clang/AST/GlobalDecl.h
===================================================================
--- clang/include/clang/AST/GlobalDecl.h
+++ clang/include/clang/AST/GlobalDecl.h
@@ -55,6 +55,7 @@
       : MultiVersionIndex(MVIndex) {
     Init(D);
   }
+  GlobalDecl(const NamedDecl *D) { Init(D); }
   GlobalDecl(const BlockDecl *D) { Init(D); }
   GlobalDecl(const CapturedDecl *D) { Init(D); }
   GlobalDecl(const ObjCMethodDecl *D) { Init(D); }
@@ -108,6 +109,8 @@
 
   void *getAsOpaquePtr() const { return Value.getOpaqueValue(); }
 
+  explicit operator bool() const { return getAsOpaquePtr(); }
+
   static GlobalDecl getFromOpaquePtr(void *P) {
     GlobalDecl GD;
     GD.Value.setFromOpaqueValue(P);
Index: clang/include/clang/AST/Mangle.h
===================================================================
--- clang/include/clang/AST/Mangle.h
+++ clang/include/clang/AST/Mangle.h
@@ -14,6 +14,7 @@
 #define LLVM_CLANG_AST_MANGLE_H
 
 #include "clang/AST/Decl.h"
+#include "clang/AST/GlobalDecl.h"
 #include "clang/AST/Type.h"
 #include "clang/Basic/ABI.h"
 #include "llvm/ADT/DenseMap.h"
@@ -96,8 +97,8 @@
   virtual bool shouldMangleStringLiteral(const StringLiteral *SL) = 0;
 
   // FIXME: consider replacing raw_ostream & with something like SmallString &.
-  void mangleName(const NamedDecl *D, raw_ostream &);
-  virtual void mangleCXXName(const NamedDecl *D, raw_ostream &) = 0;
+  void mangleName(GlobalDecl GD, raw_ostream &);
+  virtual void mangleCXXName(GlobalDecl GD, raw_ostream &) = 0;
   virtual void mangleThunk(const CXXMethodDecl *MD,
                           const ThunkInfo &Thunk,
                           raw_ostream &) = 0;
Index: clang/lib/AST/ItaniumMangle.cpp
===================================================================
--- clang/lib/AST/ItaniumMangle.cpp
+++ clang/lib/AST/ItaniumMangle.cpp
@@ -135,7 +135,7 @@
   bool shouldMangleStringLiteral(const StringLiteral *) override {
     return false;
   }
-  void mangleCXXName(const NamedDecl *D, raw_ostream &) override;
+  void mangleCXXName(GlobalDecl GD, raw_ostream &) override;
   void mangleThunk(const CXXMethodDecl *MD, const ThunkInfo &Thunk,
                    raw_ostream &) override;
   void mangleCXXDtorThunk(const CXXDestructorDecl *DD, CXXDtorType Type,
@@ -417,14 +417,14 @@
   void disableDerivedAbiTags() { DisableDerivedAbiTags = true; }
   static bool shouldHaveAbiTags(ItaniumMangleContextImpl &C, const VarDecl *VD);
 
-  void mangle(const NamedDecl *D);
+  void mangle(GlobalDecl GD);
   void mangleCallOffset(int64_t NonVirtual, int64_t Virtual);
   void mangleNumber(const llvm::APSInt &I);
   void mangleNumber(int64_t Number);
   void mangleFloat(const llvm::APFloat &F);
-  void mangleFunctionEncoding(const FunctionDecl *FD);
+  void mangleFunctionEncoding(GlobalDecl GD);
   void mangleSeqID(unsigned SeqID);
-  void mangleName(const NamedDecl *ND);
+  void mangleName(GlobalDecl GD);
   void mangleType(QualType T);
   void mangleNameOrStandardSubstitution(const NamedDecl *ND);
   void mangleLambdaSig(const CXXRecordDecl *Lambda);
@@ -461,38 +461,39 @@
 
   void mangleFunctionEncodingBareType(const FunctionDecl *FD);
 
-  void mangleNameWithAbiTags(const NamedDecl *ND,
+  void mangleNameWithAbiTags(GlobalDecl GD,
                              const AbiTagList *AdditionalAbiTags);
   void mangleModuleName(const Module *M);
   void mangleModuleNamePrefix(StringRef Name);
   void mangleTemplateName(const TemplateDecl *TD,
                           const TemplateArgument *TemplateArgs,
                           unsigned NumTemplateArgs);
-  void mangleUnqualifiedName(const NamedDecl *ND,
+  void mangleUnqualifiedName(GlobalDecl GD,
                              const AbiTagList *AdditionalAbiTags) {
-    mangleUnqualifiedName(ND, ND->getDeclName(), UnknownArity,
+    mangleUnqualifiedName(GD, cast<NamedDecl>(GD.getDecl())->getDeclName(), UnknownArity,
                           AdditionalAbiTags);
   }
-  void mangleUnqualifiedName(const NamedDecl *ND, DeclarationName Name,
+  void mangleUnqualifiedName(GlobalDecl GD, DeclarationName Name,
                              unsigned KnownArity,
                              const AbiTagList *AdditionalAbiTags);
-  void mangleUnscopedName(const NamedDecl *ND,
+  void mangleUnscopedName(GlobalDecl GD,
                           const AbiTagList *AdditionalAbiTags);
-  void mangleUnscopedTemplateName(const TemplateDecl *ND,
+  void mangleUnscopedTemplateName(GlobalDecl GD,
                                   const AbiTagList *AdditionalAbiTags);
   void mangleUnscopedTemplateName(TemplateName,
                                   const AbiTagList *AdditionalAbiTags);
   void mangleSourceName(const IdentifierInfo *II);
   void mangleRegCallName(const IdentifierInfo *II);
+  void mangleDeviceStubName(const IdentifierInfo *II);
   void mangleSourceNameWithAbiTags(
       const NamedDecl *ND, const AbiTagList *AdditionalAbiTags = nullptr);
-  void mangleLocalName(const Decl *D,
+  void mangleLocalName(GlobalDecl GD,
                        const AbiTagList *AdditionalAbiTags);
   void mangleBlockForPrefix(const BlockDecl *Block);
   void mangleUnqualifiedBlock(const BlockDecl *Block);
   void mangleTemplateParamDecl(const NamedDecl *Decl);
   void mangleLambda(const CXXRecordDecl *Lambda);
-  void mangleNestedName(const NamedDecl *ND, const DeclContext *DC,
+  void mangleNestedName(GlobalDecl GD, const DeclContext *DC,
                         const AbiTagList *AdditionalAbiTags,
                         bool NoFunction=false);
   void mangleNestedName(const TemplateDecl *TD,
@@ -501,7 +502,7 @@
   void manglePrefix(NestedNameSpecifier *qualifier);
   void manglePrefix(const DeclContext *DC, bool NoFunction=false);
   void manglePrefix(QualType type);
-  void mangleTemplatePrefix(const TemplateDecl *ND, bool NoFunction=false);
+  void mangleTemplatePrefix(GlobalDecl GD, bool NoFunction=false);
   void mangleTemplatePrefix(TemplateName Template);
   bool mangleUnresolvedTypeOrSimpleId(QualType DestroyedType,
                                       StringRef Prefix = "");
@@ -640,34 +641,36 @@
   writeAbiTags(ND, AdditionalAbiTags);
 }
 
-void CXXNameMangler::mangle(const NamedDecl *D) {
+void CXXNameMangler::mangle(GlobalDecl GD) {
   // <mangled-name> ::= _Z <encoding>
   //            ::= <data name>
   //            ::= <special-name>
   Out << "_Z";
-  if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D))
-    mangleFunctionEncoding(FD);
-  else if (const VarDecl *VD = dyn_cast<VarDecl>(D))
+  if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(GD.getDecl()))
+    mangleFunctionEncoding(GD);
+  else if (const VarDecl *VD = dyn_cast<VarDecl>(GD.getDecl()))
     mangleName(VD);
-  else if (const IndirectFieldDecl *IFD = dyn_cast<IndirectFieldDecl>(D))
+  else if (const IndirectFieldDecl *IFD =
+               dyn_cast<IndirectFieldDecl>(GD.getDecl()))
     mangleName(IFD->getAnonField());
   else
-    mangleName(cast<FieldDecl>(D));
+    mangleName(cast<FieldDecl>(GD.getDecl()));
 }
 
-void CXXNameMangler::mangleFunctionEncoding(const FunctionDecl *FD) {
+void CXXNameMangler::mangleFunctionEncoding(GlobalDecl GD) {
+  const FunctionDecl *FD = cast<FunctionDecl>(GD.getDecl());
   // <encoding> ::= <function name> <bare-function-type>
 
   // Don't mangle in the type if this isn't a decl we should typically mangle.
   if (!Context.shouldMangleDeclName(FD)) {
-    mangleName(FD);
+    mangleName(GD);
     return;
   }
 
   AbiTagList ReturnTypeAbiTags = makeFunctionReturnTypeTags(FD);
   if (ReturnTypeAbiTags.empty()) {
     // There are no tags for return type, the simplest case.
-    mangleName(FD);
+    mangleName(GD);
     mangleFunctionEncodingBareType(FD);
     return;
   }
@@ -787,13 +790,14 @@
   return isStd(cast<NamespaceDecl>(DC));
 }
 
-static const TemplateDecl *
-isTemplate(const NamedDecl *ND, const TemplateArgumentList *&TemplateArgs) {
+static const GlobalDecl
+isTemplate(GlobalDecl GD, const TemplateArgumentList *&TemplateArgs) {
+  const NamedDecl *ND = cast<NamedDecl>(GD.getDecl());
   // Check if we have a function template.
   if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(ND)) {
     if (const TemplateDecl *TD = FD->getPrimaryTemplate()) {
       TemplateArgs = FD->getTemplateSpecializationArgs();
-      return TD;
+      return GD.getWithDecl(TD);
     }
   }
 
@@ -801,20 +805,21 @@
   if (const ClassTemplateSpecializationDecl *Spec =
         dyn_cast<ClassTemplateSpecializationDecl>(ND)) {
     TemplateArgs = &Spec->getTemplateArgs();
-    return Spec->getSpecializedTemplate();
+    return GD.getWithDecl(Spec->getSpecializedTemplate());
   }
 
   // Check if we have a variable template.
   if (const VarTemplateSpecializationDecl *Spec =
           dyn_cast<VarTemplateSpecializationDecl>(ND)) {
     TemplateArgs = &Spec->getTemplateArgs();
-    return Spec->getSpecializedTemplate();
+    return GD.getWithDecl(Spec->getSpecializedTemplate());
   }
 
-  return nullptr;
+  return GlobalDecl();
 }
 
-void CXXNameMangler::mangleName(const NamedDecl *ND) {
+void CXXNameMangler::mangleName(GlobalDecl GD) {
+  const NamedDecl *ND = cast<NamedDecl>(GD.getDecl());
   if (const VarDecl *VD = dyn_cast<VarDecl>(ND)) {
     // Variables should have implicit tags from its type.
     AbiTagList VariableTypeAbiTags = makeVariableTypeTags(VD);
@@ -843,12 +848,13 @@
     // Output name with implicit tags.
     mangleNameWithAbiTags(VD, &AdditionalAbiTags);
   } else {
-    mangleNameWithAbiTags(ND, nullptr);
+    mangleNameWithAbiTags(GD, nullptr);
   }
 }
 
-void CXXNameMangler::mangleNameWithAbiTags(const NamedDecl *ND,
+void CXXNameMangler::mangleNameWithAbiTags(GlobalDecl GD,
                                            const AbiTagList *AdditionalAbiTags) {
+  const NamedDecl *ND = cast<NamedDecl>(GD.getDecl());
   //  <name> ::= [<module-name>] <nested-name>
   //         ::= [<module-name>] <unscoped-name>
   //         ::= [<module-name>] <unscoped-template-name> <template-args>
@@ -864,14 +870,14 @@
     while (!DC->isNamespace() && !DC->isTranslationUnit())
       DC = getEffectiveParentContext(DC);
   else if (GetLocalClassDecl(ND)) {
-    mangleLocalName(ND, AdditionalAbiTags);
+    mangleLocalName(GD, AdditionalAbiTags);
     return;
   }
 
   DC = IgnoreLinkageSpecDecls(DC);
 
   if (isLocalContainerContext(DC)) {
-    mangleLocalName(ND, AdditionalAbiTags);
+    mangleLocalName(GD, AdditionalAbiTags);
     return;
   }
 
@@ -886,17 +892,17 @@
   if (DC->isTranslationUnit() || isStdNamespace(DC)) {
     // Check if we have a template.
     const TemplateArgumentList *TemplateArgs = nullptr;
-    if (const TemplateDecl *TD = isTemplate(ND, TemplateArgs)) {
+    if (GlobalDecl TD = isTemplate(GD, TemplateArgs)) {
       mangleUnscopedTemplateName(TD, AdditionalAbiTags);
       mangleTemplateArgs(*TemplateArgs);
       return;
     }
 
-    mangleUnscopedName(ND, AdditionalAbiTags);
+    mangleUnscopedName(GD, AdditionalAbiTags);
     return;
   }
 
-  mangleNestedName(ND, DC, AdditionalAbiTags);
+  mangleNestedName(GD, DC, AdditionalAbiTags);
 }
 
 void CXXNameMangler::mangleModuleName(const Module *M) {
@@ -947,19 +953,21 @@
   }
 }
 
-void CXXNameMangler::mangleUnscopedName(const NamedDecl *ND,
+void CXXNameMangler::mangleUnscopedName(GlobalDecl GD,
                                         const AbiTagList *AdditionalAbiTags) {
+  const NamedDecl *ND = cast<NamedDecl>(GD.getDecl());
   //  <unscoped-name> ::= <unqualified-name>
   //                  ::= St <unqualified-name>   # ::std::
 
   if (isStdNamespace(IgnoreLinkageSpecDecls(getEffectiveDeclContext(ND))))
     Out << "St";
 
-  mangleUnqualifiedName(ND, AdditionalAbiTags);
+  mangleUnqualifiedName(GD, AdditionalAbiTags);
 }
 
 void CXXNameMangler::mangleUnscopedTemplateName(
-    const TemplateDecl *ND, const AbiTagList *AdditionalAbiTags) {
+    GlobalDecl GD, const AbiTagList *AdditionalAbiTags) {
+  const TemplateDecl *ND = cast<TemplateDecl>(GD.getDecl());
   //     <unscoped-template-name> ::= <unscoped-name>
   //                              ::= <substitution>
   if (mangleSubstitution(ND))
@@ -971,9 +979,9 @@
            "template template param cannot have abi tags");
     mangleTemplateParameter(TTP->getDepth(), TTP->getIndex());
   } else if (isa<BuiltinTemplateDecl>(ND) || isa<ConceptDecl>(ND)) {
-    mangleUnscopedName(ND, AdditionalAbiTags);
+    mangleUnscopedName(GD, AdditionalAbiTags);
   } else {
-    mangleUnscopedName(ND->getTemplatedDecl(), AdditionalAbiTags);
+    mangleUnscopedName(GD.getWithDecl(ND->getTemplatedDecl()), AdditionalAbiTags);
   }
 
   addSubstitution(ND);
@@ -1250,10 +1258,11 @@
     mangleTemplateArgs(TemplateArgs, NumTemplateArgs);
 }
 
-void CXXNameMangler::mangleUnqualifiedName(const NamedDecl *ND,
+void CXXNameMangler::mangleUnqualifiedName(GlobalDecl GD,
                                            DeclarationName Name,
                                            unsigned KnownArity,
                                            const AbiTagList *AdditionalAbiTags) {
+  const NamedDecl *ND = cast_or_null<NamedDecl>(GD.getDecl());
   unsigned Arity = KnownArity;
   //  <unqualified-name> ::= <operator-name>
   //                     ::= <ctor-dtor-name>
@@ -1499,10 +1508,11 @@
   Out << II->getLength() << II->getName();
 }
 
-void CXXNameMangler::mangleNestedName(const NamedDecl *ND,
+void CXXNameMangler::mangleNestedName(GlobalDecl GD,
                                       const DeclContext *DC,
                                       const AbiTagList *AdditionalAbiTags,
                                       bool NoFunction) {
+  const NamedDecl *ND = cast<NamedDecl>(GD.getDecl());
   // <nested-name>
   //   ::= N [<CV-qualifiers>] [<ref-qualifier>] <prefix> <unqualified-name> E
   //   ::= N [<CV-qualifiers>] [<ref-qualifier>] <template-prefix>
@@ -1520,13 +1530,13 @@
 
   // Check if we have a template.
   const TemplateArgumentList *TemplateArgs = nullptr;
-  if (const TemplateDecl *TD = isTemplate(ND, TemplateArgs)) {
+  if (GlobalDecl TD = isTemplate(GD, TemplateArgs)) {
     mangleTemplatePrefix(TD, NoFunction);
     mangleTemplateArgs(*TemplateArgs);
   }
   else {
     manglePrefix(DC, NoFunction);
-    mangleUnqualifiedName(ND, AdditionalAbiTags);
+    mangleUnqualifiedName(GD, AdditionalAbiTags);
   }
 
   Out << 'E';
@@ -1544,8 +1554,24 @@
   Out << 'E';
 }
 
-void CXXNameMangler::mangleLocalName(const Decl *D,
+static GlobalDecl getParentOfLocalEntity(const DeclContext *DC) {
+  GlobalDecl GD;
+  // The Itanium spec says:
+  // For entities in constructors and destructors, the mangling of the
+  // complete object constructor or destructor is used as the base function
+  // name, i.e. the C1 or D1 version.
+  if (auto *CD = dyn_cast<CXXConstructorDecl>(DC))
+    GD = GlobalDecl(CD, Ctor_Complete);
+  else if (auto *DD = dyn_cast<CXXDestructorDecl>(DC))
+    GD = GlobalDecl(DD, Dtor_Complete);
+  else
+    GD = GlobalDecl(dyn_cast<FunctionDecl>(DC));
+  return GD;
+}
+
+void CXXNameMangler::mangleLocalName(GlobalDecl GD,
                                      const AbiTagList *AdditionalAbiTags) {
+  const Decl *D = GD.getDecl();
   // <local-name> := Z <function encoding> E <entity name> [<discriminator>]
   //              := Z <function encoding> E s [<discriminator>]
   // <local-name> := Z <function encoding> E d [ <parameter number> ]
@@ -1565,7 +1591,7 @@
     else if (const BlockDecl *BD = dyn_cast<BlockDecl>(DC))
       mangleBlockForPrefix(BD);
     else
-      mangleFunctionEncoding(cast<FunctionDecl>(DC));
+      mangleFunctionEncoding(getParentOfLocalEntity(DC));
 
     // Implicit ABI tags (from namespace) are not available in the following
     // entity; reset to actually emitted tags, which are available.
@@ -1608,7 +1634,7 @@
       mangleUnqualifiedBlock(BD);
     } else {
       const NamedDecl *ND = cast<NamedDecl>(D);
-      mangleNestedName(ND, getEffectiveDeclContext(ND), AdditionalAbiTags,
+      mangleNestedName(GD, getEffectiveDeclContext(ND), AdditionalAbiTags,
                        true /*NoFunction*/);
     }
   } else if (const BlockDecl *BD = dyn_cast<BlockDecl>(D)) {
@@ -1629,7 +1655,7 @@
     assert(!AdditionalAbiTags && "Block cannot have additional abi tags");
     mangleUnqualifiedBlock(BD);
   } else {
-    mangleUnqualifiedName(cast<NamedDecl>(D), AdditionalAbiTags);
+    mangleUnqualifiedName(GD, AdditionalAbiTags);
   }
 
   if (const NamedDecl *ND = dyn_cast<NamedDecl>(RD ? RD : D)) {
@@ -1840,7 +1866,7 @@
 
   // Check if we have a template.
   const TemplateArgumentList *TemplateArgs = nullptr;
-  if (const TemplateDecl *TD = isTemplate(ND, TemplateArgs)) {
+  if (GlobalDecl TD = isTemplate(ND, TemplateArgs)) {
     mangleTemplatePrefix(TD);
     mangleTemplateArgs(*TemplateArgs);
   } else {
@@ -1863,7 +1889,7 @@
 
   if (OverloadedTemplateStorage *Overloaded
                                       = Template.getAsOverloadedTemplate()) {
-    mangleUnqualifiedName(nullptr, (*Overloaded->begin())->getDeclName(),
+    mangleUnqualifiedName(GlobalDecl(), (*Overloaded->begin())->getDeclName(),
                           UnknownArity, nullptr);
     return;
   }
@@ -1875,8 +1901,9 @@
   mangleUnscopedTemplateName(Template, /* AdditionalAbiTags */ nullptr);
 }
 
-void CXXNameMangler::mangleTemplatePrefix(const TemplateDecl *ND,
+void CXXNameMangler::mangleTemplatePrefix(GlobalDecl GD,
                                           bool NoFunction) {
+  const TemplateDecl *ND = cast<TemplateDecl>(GD.getDecl());
   // <template-prefix> ::= <prefix> <template unqualified-name>
   //                   ::= <template-param>
   //                   ::= <substitution>
@@ -1892,9 +1919,9 @@
   } else {
     manglePrefix(getEffectiveDeclContext(ND), NoFunction);
     if (isa<BuiltinTemplateDecl>(ND) || isa<ConceptDecl>(ND))
-      mangleUnqualifiedName(ND, nullptr);
+      mangleUnqualifiedName(GD, nullptr);
     else
-      mangleUnqualifiedName(ND->getTemplatedDecl(), nullptr);
+      mangleUnqualifiedName(GD.getWithDecl(ND->getTemplatedDecl()), nullptr);
   }
 
   addSubstitution(ND);
@@ -4943,45 +4970,44 @@
 /// and this routine will return false. In this case, the caller should just
 /// emit the identifier of the declaration (\c D->getIdentifier()) as its
 /// name.
-void ItaniumMangleContextImpl::mangleCXXName(const NamedDecl *D,
+void ItaniumMangleContextImpl::mangleCXXName(GlobalDecl GD,
                                              raw_ostream &Out) {
+  const NamedDecl *D = cast<NamedDecl>(GD.getDecl());
   assert((isa<FunctionDecl>(D) || isa<VarDecl>(D)) &&
           "Invalid mangleName() call, argument is not a variable or function!");
-  assert(!isa<CXXConstructorDecl>(D) && !isa<CXXDestructorDecl>(D) &&
-         "Invalid mangleName() call on 'structor decl!");
 
   PrettyStackTraceDecl CrashInfo(D, SourceLocation(),
                                  getASTContext().getSourceManager(),
                                  "Mangling declaration");
 
   CXXNameMangler Mangler(*this, Out, D);
-  Mangler.mangle(D);
+  Mangler.mangle(GD);
 }
 
 void ItaniumMangleContextImpl::mangleCXXCtor(const CXXConstructorDecl *D,
                                              CXXCtorType Type,
                                              raw_ostream &Out) {
   CXXNameMangler Mangler(*this, Out, D, Type);
-  Mangler.mangle(D);
+  Mangler.mangle(GlobalDecl(D, Type));
 }
 
 void ItaniumMangleContextImpl::mangleCXXDtor(const CXXDestructorDecl *D,
                                              CXXDtorType Type,
                                              raw_ostream &Out) {
   CXXNameMangler Mangler(*this, Out, D, Type);
-  Mangler.mangle(D);
+  Mangler.mangle(GlobalDecl(D, Type));
 }
 
 void ItaniumMangleContextImpl::mangleCXXCtorComdat(const CXXConstructorDecl *D,
                                                    raw_ostream &Out) {
   CXXNameMangler Mangler(*this, Out, D, Ctor_Comdat);
-  Mangler.mangle(D);
+  Mangler.mangle(GlobalDecl(D, Ctor_Comdat));
 }
 
 void ItaniumMangleContextImpl::mangleCXXDtorComdat(const CXXDestructorDecl *D,
                                                    raw_ostream &Out) {
   CXXNameMangler Mangler(*this, Out, D, Dtor_Comdat);
-  Mangler.mangle(D);
+  Mangler.mangle(GlobalDecl(D, Dtor_Comdat));
 }
 
 void ItaniumMangleContextImpl::mangleThunk(const CXXMethodDecl *MD,
@@ -5025,7 +5051,7 @@
   Mangler.mangleCallOffset(ThisAdjustment.NonVirtual,
                            ThisAdjustment.Virtual.Itanium.VCallOffsetOffset);
 
-  Mangler.mangleFunctionEncoding(DD);
+  Mangler.mangleFunctionEncoding(GlobalDecl(DD, Type));
 }
 
 /// Returns the mangled name for a guard variable for the passed in VarDecl.
Index: clang/lib/AST/Mangle.cpp
===================================================================
--- clang/lib/AST/Mangle.cpp
+++ clang/lib/AST/Mangle.cpp
@@ -114,7 +114,8 @@
   return shouldMangleCXXName(D);
 }
 
-void MangleContext::mangleName(const NamedDecl *D, raw_ostream &Out) {
+void MangleContext::mangleName(GlobalDecl GD, raw_ostream &Out) {
+  const NamedDecl *D = cast<NamedDecl>(GD.getDecl());
   // Any decl can be declared with __asm("foo") on it, and this takes precedence
   // over all other naming in the .o file.
   if (const AsmLabelAttr *ALA = D->getAttr<AsmLabelAttr>()) {
@@ -149,7 +150,7 @@
     if (const ObjCMethodDecl *OMD = dyn_cast<ObjCMethodDecl>(D))
       mangleObjCMethodName(OMD, Out);
     else
-      mangleCXXName(D, Out);
+      mangleCXXName(GD, Out);
     return;
   }
 
Index: clang/lib/AST/MicrosoftMangle.cpp
===================================================================
--- clang/lib/AST/MicrosoftMangle.cpp
+++ clang/lib/AST/MicrosoftMangle.cpp
@@ -135,7 +135,7 @@
   MicrosoftMangleContextImpl(ASTContext &Context, DiagnosticsEngine &Diags);
   bool shouldMangleCXXName(const NamedDecl *D) override;
   bool shouldMangleStringLiteral(const StringLiteral *SL) override;
-  void mangleCXXName(const NamedDecl *D, raw_ostream &Out) override;
+  void mangleCXXName(GlobalDecl GD, raw_ostream &Out) override;
   void mangleVirtualMemPtrThunk(const CXXMethodDecl *MD,
                                 const MethodVFTableLocation &ML,
                                 raw_ostream &Out) override;
@@ -2949,8 +2949,9 @@
     << Range;
 }
 
-void MicrosoftMangleContextImpl::mangleCXXName(const NamedDecl *D,
+void MicrosoftMangleContextImpl::mangleCXXName(GlobalDecl GD,
                                                raw_ostream &Out) {
+  const NamedDecl *D = cast<NamedDecl>(GD.getDecl());
   assert((isa<FunctionDecl>(D) || isa<VarDecl>(D)) &&
          "Invalid mangleName() call, argument is not a variable or function!");
   assert(!isa<CXXConstructorDecl>(D) && !isa<CXXDestructorDecl>(D) &&
Index: clang/lib/CodeGen/CGExpr.cpp
===================================================================
--- clang/lib/CodeGen/CGExpr.cpp
+++ clang/lib/CodeGen/CGExpr.cpp
@@ -2412,13 +2412,14 @@
 }
 
 static llvm::Constant *EmitFunctionDeclPointer(CodeGenModule &CGM,
-                                               const FunctionDecl *FD) {
+                                               GlobalDecl GD) {
+  const FunctionDecl *FD = cast<FunctionDecl>(GD.getDecl());
   if (FD->hasAttr<WeakRefAttr>()) {
     ConstantAddress aliasee = CGM.GetWeakRefReference(FD);
     return aliasee.getPointer();
   }
 
-  llvm::Constant *V = CGM.GetAddrOfFunction(FD);
+  llvm::Constant *V = CGM.GetAddrOfFunction(GD);
   if (!FD->hasPrototype()) {
     if (const FunctionProtoType *Proto =
             FD->getType()->getAs<FunctionProtoType>()) {
@@ -2435,9 +2436,10 @@
   return V;
 }
 
-static LValue EmitFunctionDeclLValue(CodeGenFunction &CGF,
-                                     const Expr *E, const FunctionDecl *FD) {
-  llvm::Value *V = EmitFunctionDeclPointer(CGF.CGM, FD);
+static LValue EmitFunctionDeclLValue(CodeGenFunction &CGF, const Expr *E,
+                                     GlobalDecl GD) {
+  const FunctionDecl *FD = cast<FunctionDecl>(GD.getDecl());
+  llvm::Value *V = EmitFunctionDeclPointer(CGF.CGM, GD);
   CharUnits Alignment = CGF.getContext().getDeclAlign(FD);
   return CGF.MakeAddrLValue(V, E->getType(), Alignment,
                             AlignmentSource::Decl);
@@ -4637,7 +4639,8 @@
   return EmitCall(E->getCallee()->getType(), Callee, E, ReturnValue);
 }
 
-static CGCallee EmitDirectCallee(CodeGenFunction &CGF, const FunctionDecl *FD) {
+static CGCallee EmitDirectCallee(CodeGenFunction &CGF, GlobalDecl GD) {
+  const FunctionDecl *FD = cast<FunctionDecl>(GD.getDecl());
 
   if (auto builtinID = FD->getBuiltinID()) {
     // Replaceable builtin provide their own implementation of a builtin. Unless
@@ -4649,8 +4652,8 @@
       return CGCallee::forBuiltin(builtinID, FD);
   }
 
-  llvm::Constant *calleePtr = EmitFunctionDeclPointer(CGF.CGM, FD);
-  return CGCallee::forDirect(calleePtr, GlobalDecl(FD));
+  llvm::Constant *calleePtr = EmitFunctionDeclPointer(CGF.CGM, GD);
+  return CGCallee::forDirect(calleePtr, GD);
 }
 
 CGCallee CodeGenFunction::EmitCallee(const Expr *E) {
Index: clang/lib/CodeGen/CodeGenModule.cpp
===================================================================
--- clang/lib/CodeGen/CodeGenModule.cpp
+++ clang/lib/CodeGen/CodeGenModule.cpp
@@ -1020,13 +1020,12 @@
   llvm::raw_svector_ostream Out(Buffer);
   MangleContext &MC = CGM.getCXXABI().getMangleContext();
   if (MC.shouldMangleDeclName(ND)) {
-    llvm::raw_svector_ostream Out(Buffer);
     if (const auto *D = dyn_cast<CXXConstructorDecl>(ND))
       MC.mangleCXXCtor(D, GD.getCtorType(), Out);
     else if (const auto *D = dyn_cast<CXXDestructorDecl>(ND))
       MC.mangleCXXDtor(D, GD.getDtorType(), Out);
     else
-      MC.mangleName(ND, Out);
+      MC.mangleName(GD, Out);
   } else {
     IdentifierInfo *II = ND->getIdentifier();
     assert(II && "Attempt to mangle unnamed decl.");
@@ -1034,7 +1033,6 @@
 
     if (FD &&
         FD->getType()->castAs<FunctionType>()->getCallConv() == CC_X86RegCall) {
-      llvm::raw_svector_ostream Out(Buffer);
       Out << "__regcall3__" << II->getName();
     } else {
       Out << II->getName();
@@ -4473,7 +4471,7 @@
 
   maybeSetTrivialComdat(*D, *Fn);
 
-  CodeGenFunction(*this).GenerateCode(D, Fn, FI);
+  CodeGenFunction(*this).GenerateCode(GD, Fn, FI);
 
   setNonAliasAttributes(GD, Fn);
   SetLLVMFunctionAttributesForDefinition(D, Fn);