Index: lib/LTO/LTOCodeGenerator.cpp
===================================================================
--- lib/LTO/LTOCodeGenerator.cpp
+++ lib/LTO/LTOCodeGenerator.cpp
@@ -257,6 +257,9 @@
   bool genResult = compileOptimized(&objFile.os());
   objFile.os().close();
   if (objFile.os().has_error()) {
+    std::string ErrMsg = "could not write object file: ";
+    ErrMsg += Filename;
+    emitError(ErrMsg);
     objFile.os().clear_error();
     sys::fs::remove(Twine(Filename));
     return false;