diff --git a/llvm/include/llvm/ProfileData/SampleProf.h b/llvm/include/llvm/ProfileData/SampleProf.h
--- a/llvm/include/llvm/ProfileData/SampleProf.h
+++ b/llvm/include/llvm/ProfileData/SampleProf.h
@@ -994,8 +994,6 @@
   /// Optionally scale samples by \p Weight.
   sampleprof_error merge(const FunctionSamples &Other, uint64_t Weight = 1) {
     sampleprof_error Result = sampleprof_error::success;
-    if (!GUIDToFuncNameMap)
-      GUIDToFuncNameMap = Other.GUIDToFuncNameMap;
     if (Context.getName().empty())
       Context = Other.getContext();
     if (FunctionHash == 0) {
@@ -1129,7 +1127,7 @@
   /// translate \p Name in current FunctionSamples into its original name
   /// by looking up in the function map GUIDToFuncNameMap.
   /// If the original name doesn't exist in the map, return empty StringRef.
-  StringRef getFuncName(StringRef Name) const {
+  static StringRef getFuncName(StringRef Name) {
     if (!UseMD5)
       return Name;
 
@@ -1189,7 +1187,7 @@
 
   /// GUIDToFuncNameMap saves the mapping from GUID to the symbol name, for
   /// all the function symbols defined or declared in current module.
-  DenseMap<uint64_t, StringRef> *GUIDToFuncNameMap = nullptr;
+  static LLVM_THREAD_LOCAL DenseMap<uint64_t, StringRef> *GUIDToFuncNameMap;
 
   // Assume the input \p Name is a name coming from FunctionSamples itself.
   // If UseMD5 is true, the name is already a GUID and we
@@ -1203,10 +1201,7 @@
   void findAllNames(DenseSet<StringRef> &NameSet) const;
 
   bool operator==(const FunctionSamples &Other) const {
-    return (GUIDToFuncNameMap == Other.GUIDToFuncNameMap ||
-            (GUIDToFuncNameMap && Other.GUIDToFuncNameMap &&
-             *GUIDToFuncNameMap == *Other.GUIDToFuncNameMap)) &&
-           FunctionHash == Other.FunctionHash && Context == Other.Context &&
+    return FunctionHash == Other.FunctionHash && Context == Other.Context &&
            TotalSamples == Other.TotalSamples &&
            TotalHeadSamples == Other.TotalHeadSamples &&
            BodySamples == Other.BodySamples &&
diff --git a/llvm/lib/ProfileData/SampleProf.cpp b/llvm/lib/ProfileData/SampleProf.cpp
--- a/llvm/lib/ProfileData/SampleProf.cpp
+++ b/llvm/lib/ProfileData/SampleProf.cpp
@@ -46,6 +46,8 @@
 bool FunctionSamples::UseMD5 = false;
 bool FunctionSamples::HasUniqSuffix = true;
 bool FunctionSamples::ProfileIsFS = false;
+LLVM_THREAD_LOCAL DenseMap<uint64_t, StringRef>
+    *FunctionSamples::GUIDToFuncNameMap = nullptr;
 } // namespace sampleprof
 } // namespace llvm
 
diff --git a/llvm/lib/Transforms/IPO/SampleProfile.cpp b/llvm/lib/Transforms/IPO/SampleProfile.cpp
--- a/llvm/lib/Transforms/IPO/SampleProfile.cpp
+++ b/llvm/lib/Transforms/IPO/SampleProfile.cpp
@@ -360,7 +360,7 @@
     }
 
     // Update GUIDToFuncNameMap for each function including inlinees.
-    SetGUIDToFuncNameMapForAll(&CurrentGUIDToFuncNameMap);
+    FunctionSamples::GUIDToFuncNameMap = &CurrentGUIDToFuncNameMap;
   }
 
   ~GUIDToFuncNameMapper() {
@@ -371,30 +371,10 @@
 
     // Reset GUIDToFuncNameMap for of each function as they're no
     // longer valid at this point.
-    SetGUIDToFuncNameMapForAll(nullptr);
+    FunctionSamples::GUIDToFuncNameMap = nullptr;
   }
 
 private:
-  void SetGUIDToFuncNameMapForAll(DenseMap<uint64_t, StringRef> *Map) {
-    std::queue<FunctionSamples *> FSToUpdate;
-    for (auto &IFS : CurrentReader.getProfiles()) {
-      FSToUpdate.push(&IFS.second);
-    }
-
-    while (!FSToUpdate.empty()) {
-      FunctionSamples *FS = FSToUpdate.front();
-      FSToUpdate.pop();
-      FS->GUIDToFuncNameMap = Map;
-      for (const auto &ICS : FS->getCallsiteSamples()) {
-        const FunctionSamplesMap &FSMap = ICS.second;
-        for (const auto &IFS : FSMap) {
-          FunctionSamples &FS = const_cast<FunctionSamples &>(IFS.second);
-          FSToUpdate.push(&FS);
-        }
-      }
-    }
-  }
-
   SampleProfileReader &CurrentReader;
   Module &CurrentModule;
   DenseMap<uint64_t, StringRef> &CurrentGUIDToFuncNameMap;
@@ -1148,7 +1128,8 @@
         if (auto *CB = dyn_cast<CallBase>(&I)) {
           if (!isa<IntrinsicInst>(I)) {
             if ((FS = findCalleeFunctionSamples(*CB))) {
-              assert((!FunctionSamples::UseMD5 || FS->GUIDToFuncNameMap) &&
+              assert((!FunctionSamples::UseMD5 ||
+                      FunctionSamples::GUIDToFuncNameMap) &&
                      "GUIDToFuncNameMap has to be populated");
               AllCandidates.push_back(CB);
               if (FS->getHeadSamplesEstimate() > 0 ||