diff --git a/llvm/include/llvm/IR/GlobalValue.h b/llvm/include/llvm/IR/GlobalValue.h
--- a/llvm/include/llvm/IR/GlobalValue.h
+++ b/llvm/include/llvm/IR/GlobalValue.h
@@ -491,7 +491,8 @@
   /// \c Linkage. The value is defined in module \c FileName.
   static std::string getGlobalIdentifier(StringRef Name,
                                          GlobalValue::LinkageTypes Linkage,
-                                         StringRef FileName);
+                                         StringRef FileName,
+                                         bool PreservePrefix = true);
 
   /// Return the modified name for this global value suitable to be
   /// used as the key for a global lookup (e.g. profile or ThinLTO).
diff --git a/llvm/lib/IR/Globals.cpp b/llvm/lib/IR/Globals.cpp
--- a/llvm/lib/IR/Globals.cpp
+++ b/llvm/lib/IR/Globals.cpp
@@ -131,12 +131,13 @@
 
 std::string GlobalValue::getGlobalIdentifier(StringRef Name,
                                              GlobalValue::LinkageTypes Linkage,
-                                             StringRef FileName) {
+                                             StringRef FileName,
+                                             bool PreservePrefix) {
 
   // Value names may be prefixed with a binary '1' to indicate
   // that the backend should not modify the symbols due to any platform
   // naming convention. Do not include that '1' in the PGO profile name.
-  if (Name[0] == '\1')
+  if (!PreservePrefix && Name[0] == '\1')
     Name = Name.substr(1);
 
   std::string NewName = std::string(Name);
@@ -155,7 +156,8 @@
 
 std::string GlobalValue::getGlobalIdentifier() const {
   return getGlobalIdentifier(getName(), getLinkage(),
-                             getParent()->getSourceFileName());
+                             getParent()->getSourceFileName(),
+                             /*PreservePrefix=*/true);
 }
 
 StringRef GlobalValue::getSection() const {
diff --git a/llvm/lib/ProfileData/InstrProf.cpp b/llvm/lib/ProfileData/InstrProf.cpp
--- a/llvm/lib/ProfileData/InstrProf.cpp
+++ b/llvm/lib/ProfileData/InstrProf.cpp
@@ -220,7 +220,8 @@
                            GlobalValue::LinkageTypes Linkage,
                            StringRef FileName,
                            uint64_t Version LLVM_ATTRIBUTE_UNUSED) {
-  return GlobalValue::getGlobalIdentifier(RawFuncName, Linkage, FileName);
+  return GlobalValue::getGlobalIdentifier(RawFuncName, Linkage, FileName,
+                                          /*PreservePrefix=*/false);
 }
 
 // Strip NumPrefix level of directory name from PathNameStr. If the number of
diff --git a/llvm/test/ThinLTO/X86/mangled_symbol.ll b/llvm/test/ThinLTO/X86/mangled_symbol.ll
--- a/llvm/test/ThinLTO/X86/mangled_symbol.ll
+++ b/llvm/test/ThinLTO/X86/mangled_symbol.ll
@@ -7,8 +7,10 @@
 
 ; INTERNALIZED: define internal void @extern_not_mangled
 ; INTERNALIZED: define internal void @"\01_extern_mangled"
+; INTERNALIZED: define internal void @_extern_mangled
 ; EXPORTED: define void @extern_not_mangled
 ; EXPORTED: define void @"\01_extern_mangled"
+; EXPORTED: define internal void @_extern_mangled
 
 target datalayout = "e-m:o-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-apple-macosx10.11.0"
@@ -24,3 +26,8 @@
 define void @"\01_extern_mangled"() {
   ret void
 }
+
+; _extern_mangled is different from "\01_extern_mangled"
+define void @_extern_mangled() {
+  ret void
+}