diff --git a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
@@ -670,7 +670,8 @@ static void WriteModuleInfo(const Module *M, const ValueEnumerator &VE,
   // Emit the function proto information.
   for (const Function &F : *M) {
     // FUNCTION:  [type, callingconv, isproto, linkage, paramattrs, alignment,
-    //             section, visibility, gc, unnamed_addr, prefix]
+    //             section, visibility, gc, unnamed_addr, prologuedata,
+    //             dllstorageclass, comdat, prefixdata]
     Vals.push_back(VE.getTypeID(F.getType()));
     Vals.push_back(F.getCallingConv());
     Vals.push_back(F.isDeclaration());
@@ -681,10 +682,12 @@ static void WriteModuleInfo(const Module *M, const ValueEnumerator &VE,
     Vals.push_back(getEncodedVisibility(F));
     Vals.push_back(F.hasGC() ? GCMap[F.getGC()] : 0);
     Vals.push_back(F.hasUnnamedAddr());
-    Vals.push_back(F.hasPrefixData() ? (VE.getValueID(F.getPrefixData()) + 1)
-                                      : 0);
+    Vals.push_back(F.hasPrologueData() ? (VE.getValueID(F.getPrologueData()) + 1)
+                                       : 0);
     Vals.push_back(getEncodedDLLStorageClass(F));
     Vals.push_back(F.hasComdat() ? VE.getComdatID(F.getComdat()) : 0);
+    Vals.push_back(F.hasPrefixData() ? (VE.getValueID(F.getPrefixData()) + 1)
+                                     : 0);
 
     unsigned AbbrevToUse = 0;
     Stream.EmitRecord(bitc::MODULE_CODE_FUNCTION, Vals, AbbrevToUse);

diff --git a/llvm/lib/Bitcode/Writer/ValueEnumerator.cpp b/llvm/lib/Bitcode/Writer/ValueEnumerator.cpp
@@ -85,10 +85,14 @@ static OrderMap orderModule(const Module &M) {
   for (const GlobalAlias &A : M.aliases())
     if (!isa<GlobalValue>(A.getAliasee()))
       orderValue(A.getAliasee(), OM);
-  for (const Function &F : M)
+  for (const Function &F : M) {
     if (F.hasPrefixData())
       if (!isa<GlobalValue>(F.getPrefixData()))
         orderValue(F.getPrefixData(), OM);
+    if (F.hasPrologueData())
+      if (!isa<GlobalValue>(F.getPrologueData()))
+        orderValue(F.getPrologueData(), OM);
+  }
   OM.LastGlobalConstantID = OM.size();
 
   // Initializers of GlobalValues are processed in
@@ -264,9 +268,12 @@ static UseListOrderStack predictUseListOrder(const Module &M) {
       predictValueUseListOrder(G.getInitializer(), nullptr, OM, Stack);
   for (const GlobalAlias &A : M.aliases())
     predictValueUseListOrder(A.getAliasee(), nullptr, OM, Stack);
-  for (const Function &F : M)
+  for (const Function &F : M) {
     if (F.hasPrefixData())
       predictValueUseListOrder(F.getPrefixData(), nullptr, OM, Stack);
+    if (F.hasPrologueData())
+      predictValueUseListOrder(F.getPrologueData(), nullptr, OM, Stack);
+  }
 
   return Stack;
 }
@@ -314,6 +321,11 @@ ValueEnumerator::ValueEnumerator(const Module &M) {
     if (I->hasPrefixData())
       EnumerateValue(I->getPrefixData());
 
+  // Enumerate the prologue data constants.
+  for (Module::const_iterator I = M.begin(), E = M.end(); I != E; ++I)
+    if (I->hasPrologueData())
+      EnumerateValue(I->getPrologueData());
+
   // Insert constants and metadata that are named at module level into the slot
   // pool so that the module symbol table can refer to them...
   EnumerateValueSymbolTable(M.getValueSymbolTable());

diff --git a/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp b/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
@@ -508,6 +508,10 @@ void AsmPrinter::EmitFunctionHeader() {
     OutStreamer.GetCommentOS() << '\n';
   }
 
+  // Emit the prefix data.
+  if (F->hasPrefixData())
+    EmitGlobalConstant(F->getPrefixData());
+
   // Emit the CurrentFnSym.  This is a virtual function to allow targets to
   // do their wild and crazy things as required.
   EmitFunctionEntryLabel();
@@ -528,9 +532,9 @@ void AsmPrinter::EmitFunctionHeader() {
     HI.Handler->beginFunction(MF);
   }
 
-  // Emit the prefix data.
-  if (F->hasPrefixData())
-    EmitGlobalConstant(F->getPrefixData());
+  // Emit the prologue data.
+  if (F->hasPrologueData())
+    EmitGlobalConstant(F->getPrologueData());
 }
 
 /// EmitFunctionEntryLabel - Emit the label that is the entrypoint for the

diff --git a/llvm/lib/IR/AsmWriter.cpp b/llvm/lib/IR/AsmWriter.cpp
@@ -101,6 +101,11 @@ static OrderMap orderModule(const Module *M) {
     if (F.hasPrefixData())
       if (!isa<GlobalValue>(F.getPrefixData()))
         orderValue(F.getPrefixData(), OM);
+
+    if (F.hasPrologueData())
+      if (!isa<GlobalValue>(F.getPrologueData()))
+        orderValue(F.getPrologueData(), OM);
+
     orderValue(&F, OM);
 
     if (F.isDeclaration())
@@ -1902,6 +1907,11 @@ void AssemblyWriter::printFunction(const Function *F) {
     Out << " prefix ";
     writeOperand(F->getPrefixData(), true);
   }
+  if (F->hasPrologueData()) {
+    Out << " prologue ";
+    writeOperand(F->getPrologueData(), true);
+  }
+
   if (F->isDeclaration()) {
     Out << '\n';
   } else {

diff --git a/llvm/lib/IR/Function.cpp b/llvm/lib/IR/Function.cpp
@@ -298,7 +298,7 @@ void Function::BuildLazyArguments() const {
 
   // Clear the lazy arguments bit.
   unsigned SDC = getSubclassDataFromValue();
-  const_cast<Function*>(this)->setValueSubclassData(SDC &= ~1);
+  const_cast<Function*>(this)->setValueSubclassData(SDC &= ~(1<<0));
 }
 
 size_t Function::arg_size() const {
@@ -335,8 +335,9 @@ void Function::dropAllReferences() {
   while (!BasicBlocks.empty())
     BasicBlocks.begin()->eraseFromParent();
 
-  // Prefix data is stored in a side table.
+  // Prefix and prologue data are stored in a side table.
   setPrefixData(nullptr);
+  setPrologueData(nullptr);
 }
 
 void Function::addAttribute(unsigned i, Attribute::AttrKind attr) {
@@ -416,6 +417,10 @@ void Function::copyAttributesFrom(const GlobalValue *Src) {
     setPrefixData(SrcF->getPrefixData());
   else
     setPrefixData(nullptr);
+  if (SrcF->hasPrologueData())
+    setPrologueData(SrcF->getPrologueData());
+  else
+    setPrologueData(nullptr);
 }
 
 /// getIntrinsicID - This method returns the ID number of the specified
@@ -880,11 +885,40 @@ void Function::setPrefixData(Constant *PrefixData) {
       PDHolder->setOperand(0, PrefixData);
     else
       PDHolder = ReturnInst::Create(getContext(), PrefixData);
-    SCData |= 2;
+    SCData |= (1<<1);
   } else {
     delete PDHolder;
     PDMap.erase(this);
-    SCData &= ~2;
+    SCData &= ~(1<<1);
   }
   setValueSubclassData(SCData);
 }
+
+Constant *Function::getPrologueData() const {
+  assert(hasPrologueData());
+  const LLVMContextImpl::PrologueDataMapTy &SOMap =
+      getContext().pImpl->PrologueDataMap;
+  assert(SOMap.find(this) != SOMap.end());
+  return cast<Constant>(SOMap.find(this)->second->getReturnValue());
+}
+
+void Function::setPrologueData(Constant *PrologueData) {
+  if (!PrologueData && !hasPrologueData())
+    return;
+
+  unsigned PDData = getSubclassDataFromValue();
+  LLVMContextImpl::PrologueDataMapTy &PDMap = getContext().pImpl->PrologueDataMap;
+  ReturnInst *&PDHolder = PDMap[this];
+  if (PrologueData) {
+    if (PDHolder)
+      PDHolder->setOperand(0, PrologueData);
+    else
+      PDHolder = ReturnInst::Create(getContext(), PrologueData);
+    PDData |= (1<<2);
+  } else {
+    delete PDHolder;
+    PDMap.erase(this);
+    PDData &= ~(1<<2);
+  }
+  setValueSubclassData(PDData);
+}
diff --git a/llvm/lib/IR/LLVMContextImpl.h b/llvm/lib/IR/LLVMContextImpl.h
@@ -401,6 +401,12 @@ class LLVMContextImpl {
   typedef DenseMap<const Function *, ReturnInst *> PrefixDataMapTy;
   PrefixDataMapTy PrefixDataMap;
 
+  /// \brief Mapping from a function to its prologue data, which is stored as
+  /// the operand of an unparented ReturnInst so that the prologue data has a
+  /// Use.
+  typedef DenseMap<const Function *, ReturnInst *> PrologueDataMapTy;
+  PrologueDataMapTy PrologueDataMap;
+
   int getOrAddScopeRecordIdxEntry(MDNode *N, int ExistingIdx);
   int getOrAddScopeInlinedAtIdxEntry(MDNode *Scope, MDNode *IA,int ExistingIdx);
 

diff --git a/llvm/lib/IR/TypeFinder.cpp b/llvm/lib/IR/TypeFinder.cpp
@@ -47,6 +47,9 @@ void TypeFinder::run(const Module &M, bool onlyNamed) {
     if (FI->hasPrefixData())
       incorporateValue(FI->getPrefixData());
 
+    if (FI->hasPrologueData())
+      incorporateValue(FI->getPrologueData());
+
     // First incorporate the arguments.
     for (Function::const_arg_iterator AI = FI->arg_begin(),
            AE = FI->arg_end(); AI != AE; ++AI)

diff --git a/llvm/lib/Linker/LinkModules.cpp b/llvm/lib/Linker/LinkModules.cpp
@@ -1505,11 +1505,16 @@ bool ModuleLinker::run() {
     if (DoNotLinkFromSource.count(SF)) continue;
 
     Function *DF = cast<Function>(ValueMap[SF]);
-    if (SF->hasPrefixData()) {
-      // Link in the prefix data.
+
+    // Link in the prefix data.
+    if (SF->hasPrefixData())
       DF->setPrefixData(MapValue(
           SF->getPrefixData(), ValueMap, RF_None, &TypeMap, &ValMaterializer));
-    }
+
+    // Link in the prologue data.
+    if (SF->hasPrologueData())
+      DF->setPrologueData(MapValue(
+          SF->getPrologueData(), ValueMap, RF_None, &TypeMap, &ValMaterializer));
 
     // Materialize if needed.
     if (std::error_code EC = SF->materialize())

diff --git a/llvm/lib/Transforms/IPO/GlobalDCE.cpp b/llvm/lib/Transforms/IPO/GlobalDCE.cpp
@@ -219,6 +219,9 @@ void GlobalDCE::GlobalIsNeeded(GlobalValue *G) {
     if (F->hasPrefixData())
       MarkUsedGlobalsAsNeeded(F->getPrefixData());
 
+    if (F->hasPrologueData())
+      MarkUsedGlobalsAsNeeded(F->getPrologueData());
+
     for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB)
       for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
         for (User::op_iterator U = I->op_begin(), E = I->op_end(); U != E; ++U)

diff --git a/llvm/test/CodeGen/X86/prefixdata.ll b/llvm/test/CodeGen/X86/prefixdata.ll
@@ -2,16 +2,17 @@
 
 @i = linkonce_odr global i32 1
 
-; CHECK: f:
-; CHECK-NEXT: .cfi_startproc
+; CHECK: .type f,@function
 ; CHECK-NEXT: .long	1
+; CHECK-NEXT: # 0x1
+; CHECK-NEXT: f:
 define void @f() prefix i32 1 {
   ret void
 }
 
-; CHECK: g:
-; CHECK-NEXT: .cfi_startproc
+; CHECK: .type g,@function
 ; CHECK-NEXT: .quad	i
+; CHECK-NEXT: g:
 define void @g() prefix i32* @i {
   ret void
 }
diff --git a/llvm/test/CodeGen/X86/prologuedata.ll b/llvm/test/CodeGen/X86/prologuedata.ll
@@ -0,0 +1,17 @@
+; RUN: llc < %s -mtriple=x86_64-unknown-unknown | FileCheck %s
+
+@i = linkonce_odr global i32 1
+
+; CHECK: f:
+; CHECK-NEXT: .cfi_startproc
+; CHECK-NEXT: .long	1
+define void @f() prologue i32 1 {
+  ret void
+}
+
+; CHECK: g:
+; CHECK-NEXT: .cfi_startproc
+; CHECK-NEXT: .quad	i
+define void @g() prologue i32* @i {
+  ret void
+}
diff --git a/llvm/test/Feature/prologuedata.ll b/llvm/test/Feature/prologuedata.ll
@@ -0,0 +1,18 @@
+; RUN: llvm-as < %s | llvm-dis > %t1.ll
+; RUN: FileCheck %s < %t1.ll
+; RUN: llvm-as < %t1.ll | llvm-dis > %t2.ll
+; RUN: diff %t1.ll %t2.ll
+; RUN: opt -O3 -S < %t1.ll | FileCheck %s
+
+; CHECK: @i
+@i = linkonce_odr global i32 1
+
+; CHECK: f(){{.*}}prologue i32 1
+define void @f() prologue i32 1 {
+  ret void
+}
+
+; CHECK: g(){{.*}}prologue i32* @i
+define void @g() prologue i32* @i {
+  ret void
+}
diff --git a/llvm/test/Linker/prefixdata.ll → llvm/test/Linker/prologuedata.ll b/llvm/test/Linker/prefixdata.ll → llvm/test/Linker/prologuedata.ll
@@ -3,7 +3,7 @@
 
 @i = linkonce_odr global i32 1
 
-; CHECK: define void @f() prefix i32* @i
-define void @f() prefix i32* @i {
+; CHECK: define void @f() prologue i32* @i
+define void @f() prologue i32* @i {
   ret void
 }
diff --git a/llvm/tools/verify-uselistorder/verify-uselistorder.cpp b/llvm/tools/verify-uselistorder/verify-uselistorder.cpp
@@ -197,9 +197,12 @@ ValueMapping::ValueMapping(const Module &M) {
       map(G.getInitializer());
   for (const GlobalAlias &A : M.aliases())
     map(A.getAliasee());
-  for (const Function &F : M)
+  for (const Function &F : M) {
     if (F.hasPrefixData())
       map(F.getPrefixData());
+    if (F.hasPrologueData())
+      map(F.getPrologueData());
+  }
 
   // Function bodies.
   for (const Function &F : M) {
@@ -463,9 +466,12 @@ static void changeUseLists(Module &M, Changer changeValueUseList) {
       changeValueUseList(G.getInitializer());
   for (GlobalAlias &A : M.aliases())
     changeValueUseList(A.getAliasee());
-  for (Function &F : M)
+  for (Function &F : M) {
     if (F.hasPrefixData())
       changeValueUseList(F.getPrefixData());
+    if (F.hasPrologueData())
+      changeValueUseList(F.getPrologueData());
+  }
 
   // Function bodies.
   for (Function &F : M) {