Index: lib/CodeGen/BackendUtil.cpp
===================================================================
--- lib/CodeGen/BackendUtil.cpp
+++ lib/CodeGen/BackendUtil.cpp
@@ -783,7 +783,7 @@
     break;
 
   case Backend_EmitBC:
-    if (CodeGenOpts.PrepareForThinLTO) {
+    if (CodeGenOpts.PrepareForThinLTO && !CodeGenOpts.DisableLLVMPasses) {
       if (!CodeGenOpts.ThinLinkBitcodeFile.empty()) {
         ThinLinkOS = openOutputFile(CodeGenOpts.ThinLinkBitcodeFile);
         if (!ThinLinkOS)
@@ -796,6 +796,7 @@
       // targets
       bool EmitLTOSummary =
           (CodeGenOpts.PrepareForLTO &&
+           !CodeGenOpts.DisableLLVMPasses &&
            llvm::Triple(TheModule->getTargetTriple()).getVendor() !=
                llvm::Triple::Apple);
       if (EmitLTOSummary && !TheModule->getModuleFlag("ThinLTO"))
Index: test/CodeGen/summary-index-unnamed-global.ll
===================================================================
--- /dev/null
+++ test/CodeGen/summary-index-unnamed-global.ll
@@ -0,0 +1,8 @@
+; RUN: %clang_cc1 -flto -triple x86_64-pc-linux-gnu -emit-llvm-bc -disable-llvm-passes -x ir < %s -o - | llvm-bcanalyzer -dump | FileCheck %s
+; RUN: %clang_cc1 -flto=thin -triple x86_64-pc-linux-gnu -emit-llvm-bc -disable-llvm-passes -x ir < %s -o - | llvm-bcanalyzer -dump | FileCheck %s
+
+; CHECK-NOT:GLOBALVAL_SUMMARY_BLOCK
+
+; Make sure this doesn't crash, and we don't try to emit a module summary.
+; (The command is roughly emulating what -save-temps would do.)
+@0 = global i32 0