Index: llvm/lib/CodeGen/GlobalISel/Utils.cpp
===================================================================
--- llvm/lib/CodeGen/GlobalISel/Utils.cpp
+++ llvm/lib/CodeGen/GlobalISel/Utils.cpp
@@ -205,8 +205,15 @@
     return false;
   // Replace if either DstReg has no constraints or the register
   // constraints match.
-  return !MRI.getRegClassOrRegBank(DstReg) ||
-         MRI.getRegClassOrRegBank(DstReg) == MRI.getRegClassOrRegBank(SrcReg);
+  const auto &DstRBC = MRI.getRegClassOrRegBank(DstReg);
+  if (!DstRBC || DstRBC == MRI.getRegClassOrRegBank(SrcReg))
+    return true;
+
+  // Otherwise match if the Src is already a regclass that is covered by the Dst
+  // RegBank.
+  return DstRBC.is<const RegisterBank *>() && MRI.getRegClassOrNull(SrcReg) &&
+         DstRBC.get<const RegisterBank *>()->covers(
+             *MRI.getRegClassOrNull(SrcReg));
 }
 
 bool llvm::isTriviallyDead(const MachineInstr &MI,
Index: llvm/test/CodeGen/AArch64/GlobalISel/select-constbarrier.mir
===================================================================
--- /dev/null
+++ llvm/test/CodeGen/AArch64/GlobalISel/select-constbarrier.mir
@@ -0,0 +1,58 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
+# RUN: llc -mtriple=aarch64-- -run-pass=instruction-select -verify-machineinstrs %s -o - | FileCheck %s
+
+---
+name:            test
+legalized:       true
+regBankSelected: true
+selected:        false
+tracksRegLiveness: true
+body:             |
+  ; CHECK-LABEL: name: test
+  ; CHECK: bb.0:
+  ; CHECK-NEXT:   successors: %bb.2(0x40000000), %bb.1(0x40000000)
+  ; CHECK-NEXT:   liveins: $w0, $w1
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT:   [[MOVi32imm:%[0-9]+]]:gpr32 = MOVi32imm 145185
+  ; CHECK-NEXT:   TBNZW [[MOVi32imm]], 0, %bb.2
+  ; CHECK-NEXT:   B %bb.1
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT: bb.1:
+  ; CHECK-NEXT:   successors: %bb.3(0x80000000)
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT:   $w5 = COPY [[MOVi32imm]]
+  ; CHECK-NEXT:   B %bb.3
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT: bb.2:
+  ; CHECK-NEXT:   successors: %bb.3(0x80000000)
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT:   [[ADDWrr:%[0-9]+]]:gpr32 = ADDWrr [[MOVi32imm]], [[MOVi32imm]]
+  ; CHECK-NEXT:   $w3 = COPY [[ADDWrr]]
+  ; CHECK-NEXT:   B %bb.3
+  ; CHECK-NEXT: {{  $}}
+  ; CHECK-NEXT: bb.3:
+  ; CHECK-NEXT:   RET_ReallyLR
+  bb.0:
+    successors: %bb.4(0x40000000), %bb.3(0x40000000)
+    liveins: $w0, $w1
+
+    %35:gpr(s32) = G_CONSTANT i32 145185
+    G_BRCOND %35(s32), %bb.4
+    G_BR %bb.3
+
+  bb.3:
+    successors: %bb.5(0x80000000)
+
+    %17:gpr(s32) = G_CONSTANT_FOLD_BARRIER %35
+    $w5 = COPY %17(s32)
+    G_BR %bb.5
+
+  bb.4:
+    successors: %bb.5(0x80000000)
+
+    %23:gpr(s32) = G_ADD %35, %35
+    $w3 = COPY %23(s32)
+    G_BR %bb.5
+
+  bb.5:
+    RET_ReallyLR