diff --git a/llvm/unittests/CodeGen/GlobalISel/GISelMITest.h b/llvm/unittests/CodeGen/GlobalISel/GISelMITest.h
--- a/llvm/unittests/CodeGen/GlobalISel/GISelMITest.h
+++ b/llvm/unittests/CodeGen/GlobalISel/GISelMITest.h
@@ -195,6 +195,10 @@
 
   auto OutBuffer = OutputBuf->getBuffer();
   SM.AddNewSourceBuffer(std::move(OutputBuf), SMLoc());
-  return FC.checkInput(SM, OutBuffer);
+  bool Result = FC.checkInput(SM, OutBuffer);
+  if (!Result)
+    errs() << "Full FileCheck input was:\n<<<<<<\n"
+           << OutBuffer << "\n>>>>>>\n";
+  return Result;
 }
 #endif