Index: include/llvm/ProfileData/InstrProf.h
===================================================================
--- include/llvm/ProfileData/InstrProf.h
+++ include/llvm/ProfileData/InstrProf.h
@@ -156,6 +156,10 @@
 std::string getPGOFuncName(const Function &F,
                            uint64_t Version = INSTR_PROF_INDEX_VERSION);
 
+/// Return the modified name for function \c F suitable to be
+/// used the key for profile lookup in LTO compilation.
+std::string getPGOFuncNameInLTO(const Function &F);
+
 /// Return the modified name for a function suitable to be
 /// used the key for profile lookup. The function's original
 /// name is \c RawFuncName and has linkage of type \c Linkage.
@@ -318,7 +322,7 @@
   /// A wrapper interface to populate the PGO symtab with functions
   /// decls from module \c M. This interface is used by transformation
   /// passes such as indirect function call promotion.
-  void create(const Module &M);
+  void create(const Module &M, bool InLTO = false);
   /// Create InstrProfSymtab from a set of names iteratable from
   /// \p IterRange. This interface is used by IndexedProfReader.
   template <typename NameIterRange> void create(const NameIterRange &IterRange);
Index: lib/ProfileData/InstrProf.cpp
===================================================================
--- lib/ProfileData/InstrProf.cpp
+++ lib/ProfileData/InstrProf.cpp
@@ -88,6 +88,29 @@
                         Version);
 }
 
+// Return the PGOFuncName when called in LTO optimization. LTO's
+// internalization privatizes many global linkage symbols into internal linkage.
+// This happens after value profile annotation so those internal linkage
+// function should have have a source prefix. However, we still need to
+// differentiate these symbols from the ones not from LTO's internalization:
+// In profile-use, we create a function meta-data if the PGOfuncName is
+// different from it's raw name. Use that name if it's available. Otherwise,
+// just strip off the source module prefix.
+std::string getPGOFuncNameInLTO(const Function &F) {
+  // First check if these is a metadata.
+  MDNode *MD = F.getMetadata("PGOFuncName");
+  if (MD != nullptr) {
+    StringRef S = cast<MDString>(MD->getOperand(0))->getString();
+    return S.str();
+  }
+  // Strip out prefix from the the internalized symbols.
+  std::string PGOName = getPGOFuncName(F);
+  size_t S = PGOName.find_first_of(':');
+  if (S == std::string::npos)
+    return PGOName;
+  return PGOName.substr(S + 1);
+}
+
 StringRef getFuncNameWithoutPrefix(StringRef PGOFuncName, StringRef FileName) {
   if (FileName.empty())
     return PGOFuncName;
@@ -148,9 +171,16 @@
   return createPGOFuncNameVar(*F.getParent(), F.getLinkage(), FuncName);
 }
 
-void InstrProfSymtab::create(const Module &M) {
-  for (const Function &F : M)
-    addFuncName(getPGOFuncName(F));
+void InstrProfSymtab::create(const Module &M, bool InLTO) {
+  for (const Function &F : M) {
+    // Function may not have a name. Ingore in this case.
+    if (!F.hasName())
+      continue;
+    if (InLTO)
+      addFuncName(getPGOFuncNameInLTO(F));
+    else
+      addFuncName(getPGOFuncName(F));
+  }
 
   finalizeSymtab();
 }
Index: lib/Transforms/Instrumentation/PGOInstrumentation.cpp
===================================================================
--- lib/Transforms/Instrumentation/PGOInstrumentation.cpp
+++ lib/Transforms/Instrumentation/PGOInstrumentation.cpp
@@ -246,6 +246,11 @@
                          BlockFrequencyInfo *BFI = nullptr)
       : F(Func), FunctionHash(0), MST(F, BPI, BFI) {
     FuncName = getPGOFuncName(F);
+    if (FuncName != Func.getName()) {
+      LLVMContext &C = F.getContext();
+      MDNode *N = MDNode::get(C, MDString::get(C, FuncName.c_str()));
+      F.setMetadata("PGOFuncName", N);
+    }
     computeCFGHash();
     DEBUG(dumpInfo("after CFGMST"));