2 files changed, 9 insertions, 1 deletions
diff --git a/llvm/include/llvm/LTO/LTOCodeGenerator.h b/llvm/include/llvm/LTO/LTOCodeGenerator.h
index 4f78d27b10d..91b034cd905 100644
--- a/llvm/include/llvm/LTO/LTOCodeGenerator.h
+++ b/llvm/include/llvm/LTO/LTOCodeGenerator.h
@@ -201,6 +201,7 @@ private:
 
   LLVMContext &Context;
   std::unique_ptr<Module> MergedModule;
+  bool MainModuleHasSummary = false;
   std::unique_ptr<Linker> TheLinker;
   std::unique_ptr<TargetMachine> TargetMach;
   bool EmitDwarfDebugInfo = false;
diff --git a/llvm/lib/LTO/LTOCodeGenerator.cpp b/llvm/lib/LTO/LTOCodeGenerator.cpp
index 01304641598..8497114f64f 100644
--- a/llvm/lib/LTO/LTOCodeGenerator.cpp
+++ b/llvm/lib/LTO/LTOCodeGenerator.cpp
@@ -18,6 +18,7 @@
 #include "llvm/ADT/Statistic.h"
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/Analysis/Passes.h"
+#include "llvm/Analysis/ModuleSummaryAnalysis.h"
 #include "llvm/Analysis/TargetLibraryInfo.h"
 #include "llvm/Analysis/TargetTransformInfo.h"
 #include "llvm/Bitcode/ReaderWriter.h"
@@ -145,6 +146,7 @@ void LTOCodeGenerator::setModule(std::unique_ptr<LTOModule> Mod) {
 
   MergedModule = Mod->takeModule();
   TheLinker = make_unique<Linker>(*MergedModule);
+  MainModuleHasSummary = Mod->isThinLTO();
 
   const std::vector<const char*> &Undefs = Mod->getAsmUndefinedRefs();
   for (int I = 0, E = Undefs.size(); I != E; ++I)
@@ -209,8 +211,13 @@ bool LTOCodeGenerator::writeMergedModules(const char *Path) {
     return false;
   }
 
+  std::unique_ptr<ModuleSummaryIndex> Index;
+  if (MainModuleHasSummary)
+    Index = ModuleSummaryIndexBuilder(MergedModule.get()).takeIndex();
+
   // write bitcode to it
-  WriteBitcodeToFile(MergedModule.get(), Out.os(), ShouldEmbedUselists);
+  WriteBitcodeToFile(MergedModule.get(), Out.os(), ShouldEmbedUselists,
+                     Index.get());
   Out.os().close();
 
   if (Out.os().has_error()) {