diff --git a/lib/Target/ARM/ARMExpandPseudoInsts.cpp b/lib/Target/ARM/ARMExpandPseudoInsts.cpp
index 2167ad5d746..e68a3aa8bf4 100644
--- a/lib/Target/ARM/ARMExpandPseudoInsts.cpp
+++ b/lib/Target/ARM/ARMExpandPseudoInsts.cpp
@@ -1647,7 +1647,7 @@ bool ARMExpandPseudo::ExpandCMP_SWAP(MachineBasicBlock &MBB,
            "CMP_SWAP not expected to be custom expanded for Thumb1");
     assert((UxtOp == 0 || UxtOp == ARM::tUXTB || UxtOp == ARM::tUXTH) &&
            "ARMv8-M.baseline does not have t2UXTB/t2UXTH");
-    assert(ARM::tGPRRegClass.contains(DesiredReg) &&
+    assert((UxtOp == 0 || ARM::tGPRRegClass.contains(DesiredReg)) &&
            "DesiredReg used for UXT op must be tGPR");
   }
 
diff --git a/test/CodeGen/ARM/cmpxchg.mir b/test/CodeGen/ARM/cmpxchg.mir
index 1b88dcdd7b2..dd640457fb0 100644
--- a/test/CodeGen/ARM/cmpxchg.mir
+++ b/test/CodeGen/ARM/cmpxchg.mir
@@ -1,5 +1,6 @@
 # NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
 # RUN: llc -o - %s -mtriple=armv7-unknown-linux-gnu -verify-machineinstrs -run-pass=arm-pseudo | FileCheck %s
+# RUN: llc -o - %s -mtriple=thumbv7-unknown-linux-gnu -verify-machineinstrs -run-pass=arm-pseudo | FileCheck %s --check-prefix=THUMB
 ---
 name: func
 tracksRegLiveness: true
@@ -23,5 +24,62 @@ body: |
     ; CHECK: CMPri killed $r2, 0, 14 /* CC::al */, $noreg, implicit-def $cpsr
     ; CHECK: Bcc %bb.1, 1 /* CC::ne */, killed $cpsr
     ; CHECK: .3:
+    ; THUMB-LABEL: name: func
+    ; THUMB: successors: %bb.1(0x80000000)
+    ; THUMB: liveins: $r0_r1, $r4_r5, $r3, $lr
+    ; THUMB: .1:
+    ; THUMB: successors: %bb.3(0x40000000), %bb.2(0x40000000)
+    ; THUMB: liveins: $r4, $r5, $r3
+    ; THUMB: $r0, $r1 = t2LDREXD $r3, 14 /* CC::al */, $noreg
+    ; THUMB: tCMPhir killed $r0, $r4, 14 /* CC::al */, $noreg, implicit-def $cpsr
+    ; THUMB: tCMPhir killed $r1, $r5, 0 /* CC::eq */, killed $cpsr, implicit-def $cpsr
+    ; THUMB: tBcc %bb.3, 1 /* CC::ne */, killed $cpsr
+    ; THUMB: .2:
+    ; THUMB: successors: %bb.1(0x40000000), %bb.3(0x40000000)
+    ; THUMB: liveins: $r4, $r5, $r3
+    ; THUMB: early-clobber $r2 = t2STREXD $r4, $r5, $r3, 14 /* CC::al */, $noreg
+    ; THUMB: t2CMPri killed $r2, 0, 14 /* CC::al */, $noreg, implicit-def $cpsr
+    ; THUMB: tBcc %bb.1, 1 /* CC::ne */, killed $cpsr
+    ; THUMB: .3:
     dead early-clobber renamable $r0_r1, dead early-clobber renamable $r2 = CMP_SWAP_64 killed renamable $r3, killed renamable $r4_r5, renamable $r4_r5 :: (volatile load store monotonic monotonic (s64))
 ...
+---
+name: func2
+tracksRegLiveness: true
+body: |
+  bb.0:
+    liveins: $r1, $r2, $r3, $r12, $lr
+    ; CHECK-LABEL: name: func2
+    ; CHECK: successors: %bb.1(0x80000000)
+    ; CHECK: liveins: $r1, $r2, $r3, $r12, $lr
+    ; CHECK: .1:
+    ; CHECK: successors: %bb.3(0x40000000), %bb.2(0x40000000)
+    ; CHECK: liveins: $lr, $r3, $r12
+    ; CHECK: $r1 = LDREX $r3, 14 /* CC::al */, $noreg
+    ; CHECK: CMPrr killed $r1, $r12, 14 /* CC::al */, $noreg, implicit-def $cpsr
+    ; CHECK: Bcc %bb.3, 1 /* CC::ne */, killed $cpsr
+    ; CHECK: .2:
+    ; CHECK: successors: %bb.1(0x40000000), %bb.3(0x40000000)
+    ; CHECK: liveins: $lr, $r3, $r12
+    ; CHECK: early-clobber $r2 = STREX $lr, $r3, 14 /* CC::al */, $noreg
+    ; CHECK: CMPri killed $r2, 0, 14 /* CC::al */, $noreg, implicit-def $cpsr
+    ; CHECK: Bcc %bb.1, 1 /* CC::ne */, killed $cpsr
+    ; CHECK: .3:
+    ; THUMB-LABEL: name: func2
+    ; THUMB: successors: %bb.1(0x80000000)
+    ; THUMB: liveins: $r1, $r2, $r3, $r12, $lr
+    ; THUMB: .1:
+    ; THUMB: successors: %bb.3(0x40000000), %bb.2(0x40000000)
+    ; THUMB: liveins: $lr, $r3, $r12
+    ; THUMB: $r1 = t2LDREX $r3, 0, 14 /* CC::al */, $noreg
+    ; THUMB: tCMPhir killed $r1, $r12, 14 /* CC::al */, $noreg, implicit-def $cpsr
+    ; THUMB: tBcc %bb.3, 1 /* CC::ne */, killed $cpsr
+    ; THUMB: .2:
+    ; THUMB: successors: %bb.1(0x40000000), %bb.3(0x40000000)
+    ; THUMB: liveins: $lr, $r3, $r12
+    ; THUMB: early-clobber $r2 = t2STREX $lr, $r3, 0, 14 /* CC::al */, $noreg
+    ; THUMB: t2CMPri killed $r2, 0, 14 /* CC::al */, $noreg, implicit-def $cpsr
+    ; THUMB: tBcc %bb.1, 1 /* CC::ne */, killed $cpsr
+    ; THUMB: .3:
+    dead early-clobber renamable $r1, dead early-clobber renamable $r2 = CMP_SWAP_32 killed renamable $r3, killed renamable $r12, killed renamable $lr
+...