Index: lib/CodeGen/BackendUtil.cpp
===================================================================
--- lib/CodeGen/BackendUtil.cpp
+++ lib/CodeGen/BackendUtil.cpp
@@ -847,8 +847,6 @@
       if (EmitLTOSummary) {
         if (!TheModule->getModuleFlag("ThinLTO"))
           TheModule->addModuleFlag(Module::Error, "ThinLTO", uint32_t(0));
-        TheModule->addModuleFlag(Module::Error, "EnableSplitLTOUnit",
-                                 CodeGenOpts.EnableSplitLTOUnit);
       }
 
       PerModulePasses.add(createBitcodeWriterPass(
Index: test/CodeGen/split-lto-unit.c
===================================================================
--- /dev/null
+++ test/CodeGen/split-lto-unit.c
@@ -0,0 +1,13 @@
+// ; Check that -flto=thin without -fsplit-lto-unit has EnableSplitLTOUnit = 0
+// RUN: %clang_cc1 -flto=thin -emit-llvm-bc < %s | llvm-dis -o - | FileCheck %s
+// CHECK: !{i32 1, !"EnableSplitLTOUnit", i32 0}
+//
+// ; Check that -flto=thin with -fsplit-lto-unit has EnableSplitLTOUnit = 1
+// RUN: %clang_cc1 -flto=thin -fsplit-lto-unit -emit-llvm-bc < %s | llvm-dis -o - | FileCheck %s --check-prefix=SPLIT
+// SPLIT: !{i32 1, !"EnableSplitLTOUnit", i32 1}
+//
+// ; Check that regular LTO has no EnableSplitLTOUnit flag
+// RUN: %clang_cc1 -flto -triple x86_64-pc-linux-gnu -emit-llvm-bc < %s | llvm-dis -o - | FileCheck %s --implicit-check-not="EnableSplitLTOUnit" --check-prefix=THINLTOOFF
+// THINLTOOFF: !{i32 1, !"ThinLTO", i32 0}
+
+int main() {}