Index: include/llvm/Analysis/ModuleSummaryAnalysis.h
===================================================================
--- include/llvm/Analysis/ModuleSummaryAnalysis.h
+++ include/llvm/Analysis/ModuleSummaryAnalysis.h
@@ -14,7 +14,6 @@
 #ifndef LLVM_ANALYSIS_MODULESUMMARYANALYSIS_H
 #define LLVM_ANALYSIS_MODULESUMMARYANALYSIS_H
 
-#include "llvm/ADT/Optional.h"
 #include "llvm/IR/ModuleSummaryIndex.h"
 #include "llvm/IR/PassManager.h"
 #include "llvm/Pass.h"
@@ -53,7 +52,7 @@
 
 /// Legacy wrapper pass to provide the ModuleSummaryIndex object.
 class ModuleSummaryIndexWrapperPass : public ModulePass {
-  Optional<ModuleSummaryIndex> Index;
+  std::unique_ptr<ModuleSummaryIndex> Index;
 
 public:
   static char ID;
Index: include/llvm/IR/ModuleSummaryIndex.h
===================================================================
--- include/llvm/IR/ModuleSummaryIndex.h
+++ include/llvm/IR/ModuleSummaryIndex.h
@@ -25,8 +25,10 @@
 #include "llvm/ADT/StringRef.h"
 #include "llvm/IR/GlobalValue.h"
 #include "llvm/IR/Module.h"
+#include "llvm/Support/Allocator.h"
 #include "llvm/Support/MathExtras.h"
 #include "llvm/Support/ScaledNumber.h"
+#include "llvm/Support/StringSaver.h"
 #include <algorithm>
 #include <array>
 #include <cassert>
@@ -764,6 +766,11 @@
   std::set<std::string> CfiFunctionDefs;
   std::set<std::string> CfiFunctionDecls;
 
+  // Used in cases where we want to record the name of a global, but
+  // don't have the string owned elsewhere (e.g. the Strtab on a module).
+  StringSaver Saver;
+  BumpPtrAllocator Alloc;
+
   // YAML I/O support.
   friend yaml::MappingTraits<ModuleSummaryIndex>;
 
@@ -775,7 +782,7 @@
 public:
   // See IsAnalysis variable comment.
   ModuleSummaryIndex(bool IsPerformingAnalysis)
-      : IsAnalysis(IsPerformingAnalysis) {}
+      : IsAnalysis(IsPerformingAnalysis), Saver(Alloc) {}
 
   bool isPerformingAnalysis() const { return IsAnalysis; }
 
@@ -884,6 +891,11 @@
     return ValueInfo(IsAnalysis, getOrInsertValuePtr(GUID));
   }
 
+  // Save a string in the Index. Use before passing Name to
+  // getOrInsertValueInfo when the string isn't owned elsewhere (e.g. on the
+  // module's Strtab).
+  StringRef saveString(std::string String) { return Saver.save(String); }
+
   /// Return a ValueInfo for \p GUID setting value \p Name.
   ValueInfo getOrInsertValueInfo(GlobalValue::GUID GUID, StringRef Name) {
     assert(!IsAnalysis);
Index: lib/Analysis/ModuleSummaryAnalysis.cpp
===================================================================
--- lib/Analysis/ModuleSummaryAnalysis.cpp
+++ lib/Analysis/ModuleSummaryAnalysis.cpp
@@ -607,14 +607,14 @@
 
 bool ModuleSummaryIndexWrapperPass::runOnModule(Module &M) {
   auto &PSI = *getAnalysis<ProfileSummaryInfoWrapperPass>().getPSI();
-  Index = buildModuleSummaryIndex(
+  Index = llvm::make_unique<ModuleSummaryIndex>(buildModuleSummaryIndex(
       M,
       [this](const Function &F) {
         return &(this->getAnalysis<BlockFrequencyInfoWrapperPass>(
                          *const_cast<Function *>(&F))
                      .getBFI());
       },
-      &PSI);
+      &PSI));
   return false;
 }
 
Index: lib/Bitcode/Reader/BitcodeReader.cpp
===================================================================
--- lib/Bitcode/Reader/BitcodeReader.cpp
+++ lib/Bitcode/Reader/BitcodeReader.cpp
@@ -4831,11 +4831,13 @@
   if (PrintSummaryGUIDs)
     dbgs() << "GUID " << ValueGUID << "(" << OriginalNameID << ") is "
            << ValueName << "\n";
-  
+
   // UseStrtab is false for legacy summary formats and value names are
   // created on stack. We can't use them outside of parseValueSymbolTable.
   ValueIdToValueInfoMap[ValueID] = std::make_pair(
-      TheIndex.getOrInsertValueInfo(ValueGUID, UseStrtab ? ValueName : ""),
+      TheIndex.getOrInsertValueInfo(
+          ValueGUID,
+          UseStrtab ? ValueName : TheIndex.saveString(ValueName.str())),
       OriginalNameID);
 }
 
Index: test/ThinLTO/X86/autoupgrade.ll
===================================================================
--- test/ThinLTO/X86/autoupgrade.ll
+++ test/ThinLTO/X86/autoupgrade.ll
@@ -12,6 +12,13 @@
 ; CHECK: <STRTAB_BLOCK
 ; CHECK-NEXT: blob data = 'mainglobalfunc1llvm.invariant.start.p0i8{{.*}}'
 
+; Check that the summary is able to print the names despite the lack of
+; string table in the legacy bitcode.
+; RUN: llvm-dis %p/Inputs/autoupgrade.bc -o - \
+; RUN:	   | FileCheck %s --check-prefix=SUMMARYNAMES
+; SUMMARYNAMES: ^2 = gv: (name: "globalfunc2",
+; SUMMARYNAMES: ^3 = gv: (name: "globalfunc1"
+
 target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-apple-macosx10.11.0"