diff --git a/clang/lib/CodeGen/BackendUtil.cpp b/clang/lib/CodeGen/BackendUtil.cpp
index b06c68f..4125d50 100644
--- a/clang/lib/CodeGen/BackendUtil.cpp
+++ b/clang/lib/CodeGen/BackendUtil.cpp
@@ -524,7 +524,7 @@
     PMBuilder.Inliner = createFunctionInliningPass(
         CodeGenOpts.OptimizationLevel, CodeGenOpts.OptimizeSize,
         (!CodeGenOpts.SampleProfileFile.empty() &&
-         CodeGenOpts.PrepareForThinLTO));
+         CodeGenOpts.EmitSummaryIndex));
   }
 
   PMBuilder.OptLevel = CodeGenOpts.OptimizationLevel;
@@ -534,7 +534,7 @@
 
   PMBuilder.DisableUnrollLoops = !CodeGenOpts.UnrollLoops;
   PMBuilder.MergeFunctions = CodeGenOpts.MergeFunctions;
-  PMBuilder.PrepareForThinLTO = CodeGenOpts.PrepareForThinLTO;
+  PMBuilder.PrepareForThinLTO = CodeGenOpts.EmitSummaryIndex;
   PMBuilder.PrepareForLTO = CodeGenOpts.PrepareForLTO;
   PMBuilder.RerollLoops = CodeGenOpts.RerollLoops;
 
@@ -776,7 +776,7 @@
     break;
 
   case Backend_EmitBC:
-    if (CodeGenOpts.PrepareForThinLTO) {
+    if (CodeGenOpts.EmitSummaryIndex) {
       if (!CodeGenOpts.ThinLinkBitcodeFile.empty()) {
         ThinLinkOS = openOutputFile(CodeGenOpts.ThinLinkBitcodeFile);
         if (!ThinLinkOS)
@@ -784,20 +784,10 @@
       }
       PerModulePasses.add(createWriteThinLTOBitcodePass(
           *OS, ThinLinkOS ? &ThinLinkOS->os() : nullptr));
-    } else {
-      // Emit a module summary by default for Regular LTO except for ld64
-      // targets
-      bool EmitLTOSummary =
-          (CodeGenOpts.PrepareForLTO &&
-           llvm::Triple(TheModule->getTargetTriple()).getVendor() !=
-               llvm::Triple::Apple);
-      if (EmitLTOSummary && !TheModule->getModuleFlag("ThinLTO"))
-        TheModule->addModuleFlag(Module::Error, "ThinLTO", uint32_t(0));
-
-      PerModulePasses.add(
-          createBitcodeWriterPass(*OS, CodeGenOpts.EmitLLVMUseLists,
-                                  EmitLTOSummary));
     }
+    else
+      PerModulePasses.add(
+          createBitcodeWriterPass(*OS, CodeGenOpts.EmitLLVMUseLists));
     break;
 
   case Backend_EmitLL:
@@ -945,7 +935,7 @@
   ModulePassManager MPM(CodeGenOpts.DebugPassManager);
 
   if (!CodeGenOpts.DisableLLVMPasses) {
-    bool IsThinLTO = CodeGenOpts.PrepareForThinLTO;
+    bool IsThinLTO = CodeGenOpts.EmitSummaryIndex;
     bool IsLTO = CodeGenOpts.PrepareForLTO;
 
     if (CodeGenOpts.OptimizationLevel == 0) {
@@ -1006,7 +996,7 @@
     break;
 
   case Backend_EmitBC:
-    if (CodeGenOpts.PrepareForThinLTO) {
+    if (CodeGenOpts.EmitSummaryIndex) {
       if (!CodeGenOpts.ThinLinkBitcodeFile.empty()) {
         ThinLinkOS = openOutputFile(CodeGenOpts.ThinLinkBitcodeFile);
         if (!ThinLinkOS)
@@ -1015,17 +1005,9 @@
       MPM.addPass(ThinLTOBitcodeWriterPass(*OS, ThinLinkOS ? &ThinLinkOS->os()
                                                            : nullptr));
     } else {
-      // Emit a module summary by default for Regular LTO except for ld64
-      // targets
-      bool EmitLTOSummary =
-          (CodeGenOpts.PrepareForLTO &&
-           llvm::Triple(TheModule->getTargetTriple()).getVendor() !=
-               llvm::Triple::Apple);
-      if (EmitLTOSummary && !TheModule->getModuleFlag("ThinLTO"))
-        TheModule->addModuleFlag(Module::Error, "ThinLTO", uint32_t(0));
-
       MPM.addPass(BitcodeWriterPass(*OS, CodeGenOpts.EmitLLVMUseLists,
-                                    EmitLTOSummary));
+                                    CodeGenOpts.EmitSummaryIndex,
+                                    CodeGenOpts.EmitSummaryIndex));
     }
     break;