Index: llvm/trunk/lib/MC/MCParser/AsmParser.cpp
===================================================================
--- llvm/trunk/lib/MC/MCParser/AsmParser.cpp
+++ llvm/trunk/lib/MC/MCParser/AsmParser.cpp
@@ -1103,7 +1103,7 @@
     // This is a symbol reference.
     StringRef SymbolName = Identifier;
     if (SymbolName.empty())
-      return true;
+      return Error(getLexer().getLoc(), "expected a symbol reference");
 
     MCSymbolRefExpr::VariantKind Variant = MCSymbolRefExpr::VK_None;
 
Index: llvm/trunk/test/MC/AArch64/expr-bad-symbol.s
===================================================================
--- llvm/trunk/test/MC/AArch64/expr-bad-symbol.s
+++ llvm/trunk/test/MC/AArch64/expr-bad-symbol.s
@@ -0,0 +1,6 @@
+// RUN: not llvm-mc -triple aarch64-- %s 2>&1 | FileCheck %s
+
+  .text
+_foo:
+  str q28, [x0, #1*6*4*@]
+// CHECK: error: expected a symbol reference