Index: test/tools/yaml2obj/invalid_output_file.test
===================================================================
--- /dev/null
+++ test/tools/yaml2obj/invalid_output_file.test
@@ -0,0 +1,4 @@
+# RUN: not yaml2obj -o %p/path/does/not/exist 2>&1 | FileCheck %s
+
+# Don't check the OS-dependent message "No such file or directory".
+# CHECK: yaml2obj: Error opening '{{.*}}/path/does/not/exist': {{.*}}
Index: tools/yaml2obj/yaml2obj.cpp
===================================================================
--- tools/yaml2obj/yaml2obj.cpp
+++ tools/yaml2obj/yaml2obj.cpp
@@ -80,7 +80,8 @@
   std::unique_ptr<tool_output_file> Out(
       new tool_output_file(OutputFilename, EC, sys::fs::F_None));
   if (EC) {
-    errs() << EC.message() << '\n';
+    errs() << "yaml2obj: Error opening '" << OutputFilename
+           << "': " + EC.message() << "\n";
     return 1;
   }