Index: lib/Target/ARM/ARMInstrThumb2.td
===================================================================
--- lib/Target/ARM/ARMInstrThumb2.td
+++ lib/Target/ARM/ARMInstrThumb2.td
@@ -3674,7 +3674,8 @@
 // operands, create 3 versions of the same instruction. Once there's a clean
 // framework to represent optional operands, change this behavior.
 class t2CPS<dag iops, string asm_op> : T2XI<(outs), iops, NoItinerary,
-            !strconcat("cps", asm_op), []> {
+            !strconcat("cps", asm_op), []>,
+          Requires<[IsThumb2, IsNotMClass]> {
   bits<2> imod;
   bits<3> iflags;
   bits<5> mode;
Index: lib/Target/ARM/AsmParser/ARMAsmParser.cpp
===================================================================
--- lib/Target/ARM/AsmParser/ARMAsmParser.cpp
+++ lib/Target/ARM/AsmParser/ARMAsmParser.cpp
@@ -5514,6 +5514,8 @@
     Operands.push_back(ARMOperand::CreateImm(
           MCConstantExpr::Create(ProcessorIMod, getContext()),
                                  NameLoc, NameLoc));
+  } else if (Mnemonic == "cps" && isMClass()) {
+    return Error(NameLoc, "instruction 'cps' requires effect for M-class");
   }
 
   // Add the remaining tokens in the mnemonic.
Index: test/MC/ARM/cps.s
===================================================================
--- /dev/null
+++ test/MC/ARM/cps.s
@@ -0,0 +1,17 @@
+@ RUN: llvm-mc -triple=thumbv6t2--none-eabi -show-encoding < %s | FileCheck %s
+@ RUN: llvm-mc -triple=thumbv7a--none-eabi -show-encoding < %s | FileCheck %s
+@ RUN: llvm-mc -triple=thumbv7r--none-eabi -show-encoding < %s | FileCheck %s
+@ RUN: llvm-mc -triple=thumbv8a--none-eabi -show-encoding < %s | FileCheck %s
+@ RUN: not llvm-mc -triple=thumbv7m--none-eabi -show-encoding < %s 2>&1 | FileCheck %s --check-prefix=UNDEF
+
+  cpsie f
+  cpsie i, #3
+  cps #0
+
+@ CHECK: cpsie f                         @ encoding: [0x61,0xb6]
+@ CHECK: cpsie   i, #3                   @ encoding: [0xaf,0xf3,0x43,0x85]
+@ CHECK: cps     #0                      @ encoding: [0xaf,0xf3,0x00,0x81]
+
+@ UNDEF-DAG: cpsie f                         @ encoding: [0x61,0xb6]
+@ UNDEF-DAG: error: instruction requires:
+@ UNDEF-DAG: error: instruction 'cps' requires effect for M-class