diff --git a/lib/CodeGen/VirtRegMap.cpp b/lib/CodeGen/VirtRegMap.cpp
index d7f21399826..4a06704a887 100644
--- a/lib/CodeGen/VirtRegMap.cpp
+++ b/lib/CodeGen/VirtRegMap.cpp
@@ -384,7 +384,7 @@ void VirtRegRewriter::handleIdentityCopy(MachineInstr &MI) const {
   // give us additional liveness information: The target (super-)register
   // must not be valid before this point. Replace the COPY with a KILL
   // instruction to maintain this information.
-  if (MI.getOperand(0).isUndef() || MI.getNumOperands() > 2) {
+  if (MI.getOperand(1).isUndef() || MI.getNumOperands() > 2) {
     MI.setDesc(TII->get(TargetOpcode::KILL));
     LLVM_DEBUG(dbgs() << "  replace by: " << MI);
     return;
diff --git a/test/CodeGen/AMDGPU/virtregrewrite-undef-identity-copy.mir b/test/CodeGen/AMDGPU/virtregrewrite-undef-identity-copy.mir
new file mode 100644
index 00000000000..d54d2472079
--- /dev/null
+++ b/test/CodeGen/AMDGPU/virtregrewrite-undef-identity-copy.mir
@@ -0,0 +1,69 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
+# RUN: llc -mtriple=amdgcn-amd-amdhsa -start-before=greedy -stop-after=virtregrewriter -verify-machineinstrs -o - %s | FileCheck %s
+
+# The undef copy of %4 is allocated to $vgpr3, and the identity copy
+# was deleted, and $vgpr3 was considered undef. The code to replace
+# the undef copy with a kill was incorrectly checking the dest
+# operand, rather than the source.
+
+--- |
+  define amdgpu_kernel void @undef_identity_copy() {
+    ret void
+  }
+
+  declare hidden float @bar(<4 x float>)
+  declare hidden void @foo()
+
+...
+---
+name:            undef_identity_copy
+tracksRegLiveness: true
+frameInfo:
+  maxAlignment:    4
+  hasCalls:        true
+machineFunctionInfo:
+  isEntryFunction: true
+  scratchRSrcReg:  '$sgpr0_sgpr1_sgpr2_sgpr3'
+  scratchWaveOffsetReg: '$sgpr95'
+  frameOffsetReg:  '$sgpr95'
+  stackPtrOffsetReg: '$sgpr32'
+body:             |
+  bb.0:
+    ; CHECK-LABEL: name: undef_identity_copy
+    ; CHECK: renamable $vgpr32_vgpr33_vgpr34_vgpr35 = FLAT_LOAD_DWORDX4 undef renamable $vgpr0_vgpr1, 0, 0, 0, 0, implicit $exec, implicit $flat_scr :: (load 16, addrspace 1)
+    ; CHECK: renamable $sgpr6_sgpr7 = SI_PC_ADD_REL_OFFSET target-flags(amdgpu-rel32-lo) @foo + 4, target-flags(amdgpu-rel32-hi) @foo + 4, implicit-def dead $scc
+    ; CHECK: ADJCALLSTACKUP 0, 0, implicit-def $sgpr32, implicit $sgpr32, implicit $sgpr95
+    ; CHECK: $sgpr4 = COPY $sgpr95
+    ; CHECK: dead $sgpr30_sgpr31 = SI_CALL killed renamable $sgpr6_sgpr7, @foo, csr_amdgpu_highregs, implicit $sgpr0_sgpr1_sgpr2_sgpr3, implicit $sgpr4
+    ; CHECK: ADJCALLSTACKDOWN 0, 4, implicit-def $sgpr32, implicit $sgpr32, implicit $sgpr95
+    ; CHECK: renamable $sgpr6_sgpr7 = SI_PC_ADD_REL_OFFSET target-flags(amdgpu-rel32-lo) @bar + 4, target-flags(amdgpu-rel32-hi) @bar + 4, implicit-def dead $scc
+    ; CHECK: ADJCALLSTACKUP 0, 0, implicit-def $sgpr32, implicit $sgpr32, implicit $sgpr95
+    ; CHECK: $sgpr4 = COPY $sgpr95
+    ; CHECK: $vgpr0 = COPY renamable $vgpr32
+    ; CHECK: $vgpr1 = COPY renamable $vgpr33
+    ; CHECK: $vgpr2 = COPY renamable $vgpr34
+    ; CHECK: $vgpr3 = KILL undef renamable $vgpr3
+    ; CHECK: dead $sgpr30_sgpr31 = SI_CALL killed renamable $sgpr6_sgpr7, @bar, csr_amdgpu_highregs, implicit $sgpr0_sgpr1_sgpr2_sgpr3, implicit $sgpr4, implicit $vgpr0, implicit killed $vgpr1, implicit killed $vgpr2, implicit killed $vgpr3, implicit-def $vgpr0
+    ; CHECK: ADJCALLSTACKDOWN 0, 4, implicit-def $sgpr32, implicit $sgpr32, implicit $sgpr95
+    ; CHECK: FLAT_STORE_DWORD undef renamable $vgpr0_vgpr1, killed renamable $vgpr0, 0, 0, 0, 0, implicit $exec, implicit $flat_scr :: (store 4, addrspace 1)
+    ; CHECK: S_ENDPGM 0
+    %0:vreg_128 = FLAT_LOAD_DWORDX4 undef %1:vreg_64, 0, 0, 0, 0, implicit $exec, implicit $flat_scr :: (load 16, addrspace 1)
+    %2:sreg_64 = SI_PC_ADD_REL_OFFSET target-flags(amdgpu-rel32-lo) @foo + 4, target-flags(amdgpu-rel32-hi) @foo + 4, implicit-def dead $scc
+    ADJCALLSTACKUP 0, 0, implicit-def $sgpr32, implicit $sgpr32, implicit $sgpr95
+    $sgpr4 = COPY $sgpr95
+    dead $sgpr30_sgpr31 = SI_CALL %2, @foo, csr_amdgpu_highregs, implicit $sgpr0_sgpr1_sgpr2_sgpr3, implicit $sgpr4
+    ADJCALLSTACKDOWN 0, 4, implicit-def $sgpr32, implicit $sgpr32, implicit $sgpr95
+    %3:sreg_64 = SI_PC_ADD_REL_OFFSET target-flags(amdgpu-rel32-lo) @bar + 4, target-flags(amdgpu-rel32-hi) @bar + 4, implicit-def dead $scc
+    ADJCALLSTACKUP 0, 0, implicit-def $sgpr32, implicit $sgpr32, implicit $sgpr95
+    $sgpr4 = COPY $sgpr95
+    $vgpr0 = COPY %0.sub0
+    $vgpr1 = COPY %0.sub1
+    $vgpr2 = COPY %0.sub2
+    $vgpr3 = COPY undef %4:vgpr_32
+    dead $sgpr30_sgpr31 = SI_CALL %3, @bar, csr_amdgpu_highregs, implicit $sgpr0_sgpr1_sgpr2_sgpr3, implicit $sgpr4, implicit $vgpr0, implicit killed $vgpr1, implicit killed $vgpr2, implicit killed $vgpr3, implicit-def $vgpr0
+    %5:vgpr_32 = COPY $vgpr0
+    ADJCALLSTACKDOWN 0, 4, implicit-def $sgpr32, implicit $sgpr32, implicit $sgpr95
+    FLAT_STORE_DWORD undef %6:vreg_64, %5, 0, 0, 0, 0, implicit $exec, implicit $flat_scr :: (store 4, addrspace 1)
+    S_ENDPGM 0
+
+...