Index: lib/MC/MCParser/AsmParser.cpp
===================================================================
--- lib/MC/MCParser/AsmParser.cpp
+++ lib/MC/MCParser/AsmParser.cpp
@@ -3894,6 +3894,12 @@
         parseToken(AsmToken::EndOfStatement))
       return addErrorSuffix(" in '.cfi_startproc' directive");
   }
+  
+  // TODO(kristina): Deal with PP macro expansion so the error line
+  // matches the source chunk within the diagnostic when in a PP macro.
+  if (getStreamer().hasUnfinishedDwarfFrameInfo())
+    return Error(Lexer.getLoc(),
+                 ".cfi_startproc cannot be used in an existing frame");
 
   getStreamer().EmitCFIStartProc(!Simple.empty());
   return false;