Index: clang/lib/CodeGen/CGDecl.cpp
===================================================================
--- clang/lib/CodeGen/CGDecl.cpp
+++ clang/lib/CodeGen/CGDecl.cpp
@@ -240,7 +240,7 @@
       getModule(), LTy, Ty.isConstant(getContext()), Linkage, Init, Name,
       nullptr, llvm::GlobalVariable::NotThreadLocal, TargetAS);
   GV->setAlignment(getContext().getDeclAlign(&D).getQuantity());
-  setGlobalVisibility(GV, &D, ForDefinition);
+  setGlobalVisibility(GV, &D);
 
   if (supportsCOMDAT() && GV->isWeakForLinker())
     GV->setComdat(TheModule.getOrInsertComdat(GV->getName()));
Index: clang/lib/CodeGen/CGVTT.cpp
===================================================================
--- clang/lib/CodeGen/CGVTT.cpp
+++ clang/lib/CodeGen/CGVTT.cpp
@@ -100,7 +100,7 @@
     VTT->setComdat(CGM.getModule().getOrInsertComdat(VTT->getName()));
 
   // Set the right visibility.
-  CGM.setGlobalVisibility(VTT, RD, ForDefinition);
+  CGM.setGlobalVisibility(VTT, RD);
 }
 
 llvm::GlobalVariable *CodeGenVTables::GetAddrOfVTT(const CXXRecordDecl *RD) {
Index: clang/lib/CodeGen/CGVTables.cpp
===================================================================
--- clang/lib/CodeGen/CGVTables.cpp
+++ clang/lib/CodeGen/CGVTables.cpp
@@ -51,7 +51,7 @@
 
 static void setThunkVisibility(CodeGenModule &CGM, const CXXMethodDecl *MD,
                                const ThunkInfo &Thunk, llvm::Function *Fn) {
-  CGM.setGlobalVisibility(Fn, MD, ForDefinition);
+  CGM.setGlobalVisibility(Fn, MD);
 }
 
 static void setThunkProperties(CodeGenModule &CGM, const ThunkInfo &Thunk,
@@ -730,7 +730,7 @@
   // Create the variable that will hold the construction vtable.
   llvm::GlobalVariable *VTable =
     CGM.CreateOrReplaceCXXRuntimeVariable(Name, VTType, Linkage);
-  CGM.setGlobalVisibility(VTable, RD, ForDefinition);
+  CGM.setGlobalVisibility(VTable, RD);
 
   // V-tables are always unnamed_addr.
   VTable->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global);
Index: clang/lib/CodeGen/CodeGenModule.h
===================================================================
--- clang/lib/CodeGen/CodeGenModule.h
+++ clang/lib/CodeGen/CodeGenModule.h
@@ -719,8 +719,7 @@
   llvm::ConstantInt *getSize(CharUnits numChars);
 
   /// Set the visibility for the given LLVM GlobalValue.
-  void setGlobalVisibility(llvm::GlobalValue *GV, const NamedDecl *D,
-                           ForDefinition_t IsForDefinition) const;
+  void setGlobalVisibility(llvm::GlobalValue *GV, const NamedDecl *D) const;
 
   /// Set the TLS mode for the given LLVM GlobalValue for the thread-local
   /// variable declaration D.
@@ -1272,8 +1271,7 @@
 
   /// Set function attributes for a function declaration.
   void SetFunctionAttributes(GlobalDecl GD, llvm::Function *F,
-                             bool IsIncompleteFunction, bool IsThunk,
-                             ForDefinition_t IsForDefinition);
+                             bool IsIncompleteFunction, bool IsThunk);
 
   void EmitGlobalDefinition(GlobalDecl D, llvm::GlobalValue *GV = nullptr);
 
Index: clang/lib/CodeGen/CodeGenModule.cpp
===================================================================
--- clang/lib/CodeGen/CodeGenModule.cpp
+++ clang/lib/CodeGen/CodeGenModule.cpp
@@ -700,8 +700,7 @@
 }
 
 void CodeGenModule::setGlobalVisibility(llvm::GlobalValue *GV,
-                                        const NamedDecl *D,
-                                        ForDefinition_t IsForDefinition) const {
+                                        const NamedDecl *D) const {
   if (GV->hasDLLImportStorageClass())
     return;
   // Internal definitions always have default visibility.
@@ -712,8 +711,7 @@
 
   // Set visibility for definitions.
   LinkageInfo LV = D->getLinkageAndVisibility();
-  if (LV.isVisibilityExplicit() ||
-      (IsForDefinition && !GV->hasAvailableExternallyLinkage()))
+  if (LV.isVisibilityExplicit() || !GV->isDeclarationForLinker())
     GV->setVisibility(GetLLVMVisibility(LV.getVisibility()));
 }
 
@@ -1174,7 +1172,7 @@
 void CodeGenModule::SetCommonAttributes(const Decl *D,
                                         llvm::GlobalValue *GV) {
   if (const auto *ND = dyn_cast_or_null<NamedDecl>(D))
-    setGlobalVisibility(GV, ND, ForDefinition);
+    setGlobalVisibility(GV, ND);
   else
     GV->setVisibility(llvm::GlobalValue::DefaultVisibility);
 
@@ -1216,7 +1214,7 @@
       GO->setSection(SA->getName());
   }
 
-  getTargetCodeGenInfo().setTargetAttributes(D, GO, *this, ForDefinition);
+  getTargetCodeGenInfo().setTargetAttributes(D, GO, *this);
 }
 
 void CodeGenModule::SetInternalFunctionAttributes(const Decl *D,
@@ -1280,8 +1278,7 @@
 
 void CodeGenModule::SetFunctionAttributes(GlobalDecl GD, llvm::Function *F,
                                           bool IsIncompleteFunction,
-                                          bool IsThunk,
-                                          ForDefinition_t IsForDefinition) {
+                                          bool IsThunk) {
 
   if (llvm::Intrinsic::ID IID = F->getIntrinsicID()) {
     // If this is an intrinsic function, set the function's attributes
@@ -1295,9 +1292,8 @@
   if (!IsIncompleteFunction) {
     SetLLVMFunctionAttributes(FD, getTypes().arrangeGlobalDeclaration(GD), F);
     // Setup target-specific attributes.
-    if (!IsForDefinition)
-      getTargetCodeGenInfo().setTargetAttributes(FD, F, *this,
-                                                 NotForDefinition);
+    if (F->isDeclaration())
+      getTargetCodeGenInfo().setTargetAttributes(FD, F, *this);
   }
 
   // Add the Returned attribute for "this", except for iOS 5 and earlier
@@ -1316,7 +1312,7 @@
   // overridden by a definition.
 
   setLinkageForGV(F, FD);
-  setGlobalVisibility(F, FD, NotForDefinition);
+  setGlobalVisibility(F, FD);
 
   if (FD->getAttr<PragmaClangTextSectionAttr>()) {
     F->addFnAttr("implicit-section-name");
@@ -2350,8 +2346,7 @@
 
   assert(F->getName() == MangledName && "name was uniqued!");
   if (D)
-    SetFunctionAttributes(GD, F, IsIncompleteFunction, IsThunk,
-                          IsForDefinition);
+    SetFunctionAttributes(GD, F, IsIncompleteFunction, IsThunk);
   if (ExtraAttrs.hasAttributes(llvm::AttributeList::FunctionIndex)) {
     llvm::AttrBuilder B(ExtraAttrs, llvm::AttributeList::FunctionIndex);
     F->addAttributes(llvm::AttributeList::FunctionIndex, B);
@@ -2638,7 +2633,7 @@
     GV->setAlignment(getContext().getDeclAlign(D).getQuantity());
 
     setLinkageForGV(GV, D);
-    setGlobalVisibility(GV, D, NotForDefinition);
+    setGlobalVisibility(GV, D);
 
     if (D->getTLSKind()) {
       if (D->getTLSKind() == VarDecl::TLS_Dynamic)
@@ -3457,7 +3452,7 @@
   setFunctionDLLStorageClass(GD, Fn);
 
   // FIXME: this is redundant with part of setFunctionDefinitionAttributes
-  setGlobalVisibility(Fn, D, ForDefinition);
+  setGlobalVisibility(Fn, D);
 
   MaybeHandleStaticInExternC(D, Fn);
 
@@ -4053,7 +4048,7 @@
       getModule(), Type, Constant, Linkage, InitialValue, Name.c_str(),
       /*InsertBefore=*/nullptr, llvm::GlobalVariable::NotThreadLocal, TargetAS);
   if (emitter) emitter->finalize(GV);
-  setGlobalVisibility(GV, VD, ForDefinition);
+  setGlobalVisibility(GV, VD);
   GV->setAlignment(Align.getQuantity());
   if (supportsCOMDAT() && GV->isWeakForLinker())
     GV->setComdat(TheModule.getOrInsertComdat(GV->getName()));
Index: clang/lib/CodeGen/ItaniumCXXABI.cpp
===================================================================
--- clang/lib/CodeGen/ItaniumCXXABI.cpp
+++ clang/lib/CodeGen/ItaniumCXXABI.cpp
@@ -1531,7 +1531,7 @@
     VTable->setComdat(CGM.getModule().getOrInsertComdat(VTable->getName()));
 
   // Set the right visibility.
-  CGM.setGlobalVisibility(VTable, RD, ForDefinition);
+  CGM.setGlobalVisibility(VTable, RD);
 
   // Use pointer alignment for the vtable. Otherwise we would align them based
   // on the size of the initializer which doesn't make sense as only single
@@ -1641,7 +1641,7 @@
   VTable = CGM.CreateOrReplaceCXXRuntimeVariable(
       Name, VTableType, llvm::GlobalValue::ExternalLinkage);
   VTable->setUnnamedAddr(llvm::GlobalValue::UnnamedAddr::Global);
-  CGM.setGlobalVisibility(VTable, RD, NotForDefinition);
+  CGM.setGlobalVisibility(VTable, RD);
 
   if (RD->hasAttr<DLLImportAttr>())
     VTable->setDLLStorageClass(llvm::GlobalValue::DLLImportStorageClass);
Index: clang/lib/CodeGen/TargetInfo.h
===================================================================
--- clang/lib/CodeGen/TargetInfo.h
+++ clang/lib/CodeGen/TargetInfo.h
@@ -57,8 +57,7 @@
   /// setTargetAttributes - Provides a convenient hook to handle extra
   /// target-specific attributes for the given global.
   virtual void setTargetAttributes(const Decl *D, llvm::GlobalValue *GV,
-                                   CodeGen::CodeGenModule &M,
-                                   ForDefinition_t IsForDefinition) const {}
+                                   CodeGen::CodeGenModule &M) const {}
 
   /// emitTargetMD - Provides a convenient hook to handle extra
   /// target-specific metadata for the given global.
Index: clang/lib/CodeGen/TargetInfo.cpp
===================================================================
--- clang/lib/CodeGen/TargetInfo.cpp
+++ clang/lib/CodeGen/TargetInfo.cpp
@@ -1052,8 +1052,7 @@
       const llvm::Triple &Triple, const CodeGenOptions &Opts);
 
   void setTargetAttributes(const Decl *D, llvm::GlobalValue *GV,
-                           CodeGen::CodeGenModule &CGM,
-                           ForDefinition_t IsForDefinition) const override;
+                           CodeGen::CodeGenModule &CGM) const override;
 
   int getDwarfEHStackPointer(CodeGen::CodeGenModule &CGM) const override {
     // Darwin uses different dwarf register numbers for EH.
@@ -1920,9 +1919,8 @@
 }
 
 void X86_32TargetCodeGenInfo::setTargetAttributes(
-    const Decl *D, llvm::GlobalValue *GV, CodeGen::CodeGenModule &CGM,
-    ForDefinition_t IsForDefinition) const {
-  if (!IsForDefinition)
+    const Decl *D, llvm::GlobalValue *GV, CodeGen::CodeGenModule &CGM) const {
+  if (GV->isDeclaration())
     return;
   if (const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(D)) {
     if (FD->hasAttr<X86ForceAlignArgPointerAttr>()) {
@@ -2279,9 +2277,8 @@
   }
 
   void setTargetAttributes(const Decl *D, llvm::GlobalValue *GV,
-                           CodeGen::CodeGenModule &CGM,
-                           ForDefinition_t IsForDefinition) const override {
-    if (!IsForDefinition)
+                           CodeGen::CodeGenModule &CGM) const override {
+    if (GV->isDeclaration())
       return;
     if (const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(D)) {
       if (FD->hasAttr<X86ForceAlignArgPointerAttr>()) {
@@ -2339,8 +2336,7 @@
         Win32StructABI, NumRegisterParameters, false) {}
 
   void setTargetAttributes(const Decl *D, llvm::GlobalValue *GV,
-                           CodeGen::CodeGenModule &CGM,
-                           ForDefinition_t IsForDefinition) const override;
+                           CodeGen::CodeGenModule &CGM) const override;
 
   void getDependentLibraryOption(llvm::StringRef Lib,
                                  llvm::SmallString<24> &Opt) const override {
@@ -2369,10 +2365,9 @@
 }
 
 void WinX86_32TargetCodeGenInfo::setTargetAttributes(
-    const Decl *D, llvm::GlobalValue *GV, CodeGen::CodeGenModule &CGM,
-    ForDefinition_t IsForDefinition) const {
-  X86_32TargetCodeGenInfo::setTargetAttributes(D, GV, CGM, IsForDefinition);
-  if (!IsForDefinition)
+    const Decl *D, llvm::GlobalValue *GV, CodeGen::CodeGenModule &CGM) const {
+  X86_32TargetCodeGenInfo::setTargetAttributes(D, GV, CGM);
+  if (GV->isDeclaration())
     return;
   addStackProbeSizeTargetAttribute(D, GV, CGM);
 }
@@ -2384,8 +2379,7 @@
       : TargetCodeGenInfo(new WinX86_64ABIInfo(CGT)) {}
 
   void setTargetAttributes(const Decl *D, llvm::GlobalValue *GV,
-                           CodeGen::CodeGenModule &CGM,
-                           ForDefinition_t IsForDefinition) const override;
+                           CodeGen::CodeGenModule &CGM) const override;
 
   int getDwarfEHStackPointer(CodeGen::CodeGenModule &CGM) const override {
     return 7;
@@ -2415,10 +2409,9 @@
 };
 
 void WinX86_64TargetCodeGenInfo::setTargetAttributes(
-    const Decl *D, llvm::GlobalValue *GV, CodeGen::CodeGenModule &CGM,
-    ForDefinition_t IsForDefinition) const {
-  TargetCodeGenInfo::setTargetAttributes(D, GV, CGM, IsForDefinition);
-  if (!IsForDefinition)
+    const Decl *D, llvm::GlobalValue *GV, CodeGen::CodeGenModule &CGM) const {
+  TargetCodeGenInfo::setTargetAttributes(D, GV, CGM);
+  if (GV->isDeclaration())
     return;
   if (const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(D)) {
     if (FD->hasAttr<X86ForceAlignArgPointerAttr>()) {
@@ -5557,9 +5550,8 @@
   }
 
   void setTargetAttributes(const Decl *D, llvm::GlobalValue *GV,
-                           CodeGen::CodeGenModule &CGM,
-                           ForDefinition_t IsForDefinition) const override {
-    if (!IsForDefinition)
+                           CodeGen::CodeGenModule &CGM) const override {
+    if (GV->isDeclaration())
       return;
     const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(D);
     if (!FD)
@@ -5602,8 +5594,7 @@
       : ARMTargetCodeGenInfo(CGT, K) {}
 
   void setTargetAttributes(const Decl *D, llvm::GlobalValue *GV,
-                           CodeGen::CodeGenModule &CGM,
-                           ForDefinition_t IsForDefinition) const override;
+                           CodeGen::CodeGenModule &CGM) const override;
 
   void getDependentLibraryOption(llvm::StringRef Lib,
                                  llvm::SmallString<24> &Opt) const override {
@@ -5617,10 +5608,9 @@
 };
 
 void WindowsARMTargetCodeGenInfo::setTargetAttributes(
-    const Decl *D, llvm::GlobalValue *GV, CodeGen::CodeGenModule &CGM,
-    ForDefinition_t IsForDefinition) const {
-  ARMTargetCodeGenInfo::setTargetAttributes(D, GV, CGM, IsForDefinition);
-  if (!IsForDefinition)
+    const Decl *D, llvm::GlobalValue *GV, CodeGen::CodeGenModule &CGM) const {
+  ARMTargetCodeGenInfo::setTargetAttributes(D, GV, CGM);
+  if (GV->isDeclaration())
     return;
   addStackProbeSizeTargetAttribute(D, GV, CGM);
 }
@@ -6149,8 +6139,7 @@
     : TargetCodeGenInfo(new NVPTXABIInfo(CGT)) {}
 
   void setTargetAttributes(const Decl *D, llvm::GlobalValue *GV,
-                           CodeGen::CodeGenModule &M,
-                           ForDefinition_t IsForDefinition) const override;
+                           CodeGen::CodeGenModule &M) const override;
 
 private:
   // Adds a NamedMDNode with F, Name, and Operand as operands, and adds the
@@ -6206,9 +6195,8 @@
 }
 
 void NVPTXTargetCodeGenInfo::setTargetAttributes(
-    const Decl *D, llvm::GlobalValue *GV, CodeGen::CodeGenModule &M,
-    ForDefinition_t IsForDefinition) const {
-  if (!IsForDefinition)
+    const Decl *D, llvm::GlobalValue *GV, CodeGen::CodeGenModule &M) const {
+  if (GV->isDeclaration())
     return;
   const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(D);
   if (!FD) return;
@@ -6644,16 +6632,14 @@
   MSP430TargetCodeGenInfo(CodeGenTypes &CGT)
     : TargetCodeGenInfo(new DefaultABIInfo(CGT)) {}
   void setTargetAttributes(const Decl *D, llvm::GlobalValue *GV,
-                           CodeGen::CodeGenModule &M,
-                           ForDefinition_t IsForDefinition) const override;
+                           CodeGen::CodeGenModule &M) const override;
 };
 
 }
 
 void MSP430TargetCodeGenInfo::setTargetAttributes(
-    const Decl *D, llvm::GlobalValue *GV, CodeGen::CodeGenModule &M,
-    ForDefinition_t IsForDefinition) const {
-  if (!IsForDefinition)
+    const Decl *D, llvm::GlobalValue *GV, CodeGen::CodeGenModule &M) const {
+  if (GV->isDeclaration())
     return;
   if (const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(D)) {
     if (const MSP430InterruptAttr *attr = FD->getAttr<MSP430InterruptAttr>()) {
@@ -6713,8 +6699,7 @@
   }
 
   void setTargetAttributes(const Decl *D, llvm::GlobalValue *GV,
-                           CodeGen::CodeGenModule &CGM,
-                           ForDefinition_t IsForDefinition) const override {
+                           CodeGen::CodeGenModule &CGM) const override {
     const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(D);
     if (!FD) return;
     llvm::Function *Fn = cast<llvm::Function>(GV);
@@ -6725,7 +6710,7 @@
       Fn->addFnAttr("short-call");
 
     // Other attributes do not have a meaning for declarations.
-    if (!IsForDefinition)
+    if (GV->isDeclaration())
       return;
 
     if (FD->hasAttr<Mips16Attr>()) {
@@ -7089,9 +7074,8 @@
     : TargetCodeGenInfo(new DefaultABIInfo(CGT)) { }
 
   void setTargetAttributes(const Decl *D, llvm::GlobalValue *GV,
-                           CodeGen::CodeGenModule &CGM,
-                           ForDefinition_t IsForDefinition) const override {
-    if (!IsForDefinition)
+                           CodeGen::CodeGenModule &CGM) const override {
+    if (GV->isDeclaration())
       return;
     const auto *FD = dyn_cast_or_null<FunctionDecl>(D);
     if (!FD) return;
@@ -7120,14 +7104,12 @@
     : DefaultTargetCodeGenInfo(CGT) {}
 
   void setTargetAttributes(const Decl *D, llvm::GlobalValue *GV,
-                           CodeGen::CodeGenModule &M,
-                           ForDefinition_t IsForDefinition) const override;
+                           CodeGen::CodeGenModule &M) const override;
 };
 
 void TCETargetCodeGenInfo::setTargetAttributes(
-    const Decl *D, llvm::GlobalValue *GV, CodeGen::CodeGenModule &M,
-    ForDefinition_t IsForDefinition) const {
-  if (!IsForDefinition)
+    const Decl *D, llvm::GlobalValue *GV, CodeGen::CodeGenModule &M) const {
+  if (GV->isDeclaration())
     return;
   const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(D);
   if (!FD) return;
@@ -7632,8 +7614,7 @@
   AMDGPUTargetCodeGenInfo(CodeGenTypes &CGT)
     : TargetCodeGenInfo(new AMDGPUABIInfo(CGT)) {}
   void setTargetAttributes(const Decl *D, llvm::GlobalValue *GV,
-                           CodeGen::CodeGenModule &M,
-                           ForDefinition_t IsForDefinition) const override;
+                           CodeGen::CodeGenModule &M) const override;
   unsigned getOpenCLKernelCallingConv() const override;
 
   llvm::Constant *getNullPointer(const CodeGen::CodeGenModule &CGM,
@@ -7655,9 +7636,8 @@
 }
 
 void AMDGPUTargetCodeGenInfo::setTargetAttributes(
-    const Decl *D, llvm::GlobalValue *GV, CodeGen::CodeGenModule &M,
-    ForDefinition_t IsForDefinition) const {
-  if (!IsForDefinition)
+    const Decl *D, llvm::GlobalValue *GV, CodeGen::CodeGenModule &M) const {
+  if (GV->isDeclaration())
     return;
   const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(D);
   if (!FD)