Index: llvm/lib/MC/MCParser/AsmParser.cpp
===================================================================
--- llvm/lib/MC/MCParser/AsmParser.cpp
+++ llvm/lib/MC/MCParser/AsmParser.cpp
@@ -1798,6 +1798,8 @@
                                        RewrittenLabel);
         IDVal = RewrittenLabel;
       }
+      if (IDVal.empty())
+        return Error(IDLoc, "expected a symbol reference.");
       Sym = getContext().getOrCreateSymbol(IDVal);
     } else
       Sym = Ctx.createDirectionalLocalSymbol(LocalLabelVal);