Index: lib/Target/ARM/AsmParser/ARMAsmParser.cpp
===================================================================
--- lib/Target/ARM/AsmParser/ARMAsmParser.cpp
+++ lib/Target/ARM/AsmParser/ARMAsmParser.cpp
@@ -4330,7 +4330,7 @@
 
       // If some specific flag is already set, it means that some letter is
       // present more than once, this is not acceptable.
-      if (FlagsVal == ~0U || (FlagsVal & Flag))
+      if (Flag == ~0U || (FlagsVal & Flag))
         return MatchOperand_NoMatch;
       FlagsVal |= Flag;
     }
Index: test/MC/ARM/invalid-special-reg.s
===================================================================
--- /dev/null
+++ test/MC/ARM/invalid-special-reg.s
@@ -0,0 +1,11 @@
+@ RUN: not llvm-mc -triple armv7a--none-eabi < %s |& FileCheck %s
+@ RUN: not llvm-mc -triple thumbv7a--none-eabi < %s |& FileCheck %s
+
+  msr apsr_c, r0
+@ CHECK: invalid operand for instruction
+  msr cpsr_w
+@ CHECK: invalid operand for instruction
+  msr cpsr_cc
+@ CHECK: invalid operand for instruction
+  msr xpsr_c
+@ CHECK: invalid operand for instruction