Index: lib/Target/ARM/ARMInstrThumb2.td
===================================================================
--- lib/Target/ARM/ARMInstrThumb2.td
+++ lib/Target/ARM/ARMInstrThumb2.td
@@ -3309,7 +3309,8 @@
                          (ins addr_offset_none:$addr),
                          AddrModeNone, 4, NoItinerary,
                          "ldrexd", "\t$Rt, $Rt2, $addr", "",
-                         [], {?, ?, ?, ?}> {
+                         [], {?, ?, ?, ?}>,
+               Requires<[IsThumb2, IsNotMClass]> {
   bits<4> Rt2;
   let Inst{11-8} = Rt2;
 }
@@ -3385,7 +3386,8 @@
                          (ins rGPR:$Rt, rGPR:$Rt2, addr_offset_none:$addr),
                          AddrModeNone, 4, NoItinerary,
                          "strexd", "\t$Rd, $Rt, $Rt2, $addr", "", [],
-                         {?, ?, ?, ?}> {
+                         {?, ?, ?, ?}>,
+               Requires<[IsThumb2, IsNotMClass]> {
   bits<4> Rt2;
   let Inst{11-8} = Rt2;
 }
Index: test/MC/ARM/thumb2-ldrexd-strexd.s
===================================================================
--- /dev/null
+++ test/MC/ARM/thumb2-ldrexd-strexd.s
@@ -0,0 +1,14 @@
+@ 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
+
+  ldrexd r0, r1, [r2]
+  strexd r3, r4, r5, [r6]
+
+@ CHECK: ldrexd r0, r1, [r2]            @ encoding: [0xd2,0xe8,0x7f,0x01]
+@ CHECK: strexd r3, r4, r5, [r6]        @ encoding: [0xc6,0xe8,0x73,0x45]
+
+@ UNDEF: error: instruction requires: !armv*m
+@ UNDEF: error: instruction requires: !armv*m