Index: lib/CodeGen/GlobalISel/RegisterBankInfo.cpp
===================================================================
--- lib/CodeGen/GlobalISel/RegisterBankInfo.cpp
+++ lib/CodeGen/GlobalISel/RegisterBankInfo.cpp
@@ -207,10 +207,19 @@
         continue;
       }
     }
-    const ValueMapping *ValMapping =
-        &getValueMapping(0, getSizeInBits(Reg, MRI, TRI), *CurRegBank);
+
+    unsigned Size = getSizeInBits(Reg, MRI, TRI);
+    const ValueMapping *ValMapping = &getValueMapping(0, Size, *CurRegBank);
     if (IsCopyLike) {
-      OperandsMapping[0] = ValMapping;
+      if (MI.isRegSequence()) {
+        // For reg_sequence, the result size does not match the input.
+        unsigned ResultSize = getSizeInBits(MI.getOperand(0).getReg(),
+                                            MRI, TRI);
+        OperandsMapping[0] = &getValueMapping(0, ResultSize, *CurRegBank);
+      } else {
+        OperandsMapping[0] = ValMapping;
+      }
+
       CompleteMapping = true;
       break;
     }
Index: test/CodeGen/AArch64/GlobalISel/regbankselect-reg_sequence.mir
===================================================================
--- test/CodeGen/AArch64/GlobalISel/regbankselect-reg_sequence.mir
+++ test/CodeGen/AArch64/GlobalISel/regbankselect-reg_sequence.mir
@@ -1,7 +1,4 @@
 # RUN: llc %s -mtriple aarch64-- -o - -run-pass regbankselect | FileCheck %s
---- |
-  define void @foo() { ret void }
-...
 ---
 # CHECK-LABEL: foo
 # Check that we produce a valid mapping for REG_SEQUENCE.
@@ -10,16 +7,16 @@
 # whereas since REG_SEQUENCE are kind of target opcode
 # their definition may not have a type.
 #
-# CHECK: id: 0, class: dd
+
+# CHECK: %0:fpr(s128) = REG_SEQUENCE $d0, %subreg.dsub0, $d1, %subreg.dsub1
+
 name: foo
 legalized: true
 tracksRegLiveness: true
-registers:
-  - { id: 0, class: dd }
 body: |
   bb.0:
     liveins: $d0, $d1
 
-    %0 = REG_SEQUENCE $d0, %subreg.dsub0, $d1, %subreg.dsub1
+    %0:_(s128) = REG_SEQUENCE $d0, %subreg.dsub0, $d1, %subreg.dsub1
 
 ...
Index: test/CodeGen/AMDGPU/GlobalISel/regbankselect-reg-sequence.mir
===================================================================
--- /dev/null
+++ test/CodeGen/AMDGPU/GlobalISel/regbankselect-reg-sequence.mir
@@ -0,0 +1,140 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py
+# RUN: llc -march=amdgcn -mcpu=fiji -run-pass=regbankselect %s -verify-machineinstrs -o - -regbankselect-fast | FileCheck %s
+# RUN: llc -march=amdgcn -mcpu=fiji -run-pass=regbankselect %s -verify-machineinstrs -o - -regbankselect-greedy | FileCheck %s
+
+---
+name: reg_sequence_ss_vreg
+legalized: true
+tracksRegLiveness: true
+
+body: |
+  bb.0:
+    liveins: $sgpr0, $sgpr1
+
+    ; CHECK-LABEL: name: reg_sequence_ss_vreg
+    ; CHECK: liveins: $sgpr0, $sgpr1
+    ; CHECK: [[COPY:%[0-9]+]]:sgpr(s32) = COPY $sgpr0
+    ; CHECK: [[COPY1:%[0-9]+]]:sgpr(s32) = COPY $sgpr1
+    ; CHECK: [[REG_SEQUENCE:%[0-9]+]]:sgpr(s64) = REG_SEQUENCE [[COPY]](s32), %subreg.sub0, [[COPY1]](s32), %subreg.sub1
+    %0:_(s32) = COPY $sgpr0
+    %1:_(s32) = COPY $sgpr1
+    %2:_(s64) = REG_SEQUENCE %0, %subreg.sub0, %1, %subreg.sub1
+...
+
+---
+name: reg_sequence_ss_physreg
+legalized: true
+tracksRegLiveness: true
+
+body: |
+  bb.0:
+    liveins: $sgpr0, $sgpr1
+
+    ; CHECK-LABEL: name: reg_sequence_ss_physreg
+    ; CHECK: liveins: $sgpr0, $sgpr1
+    ; CHECK: [[REG_SEQUENCE:%[0-9]+]]:sgpr(s64) = REG_SEQUENCE $sgpr0, %subreg.sub0, $sgpr1, %subreg.sub1
+    %0:_(s64) = REG_SEQUENCE $sgpr0, %subreg.sub0, $sgpr1, %subreg.sub1
+...
+
+---
+name: reg_sequence_sv_vreg
+legalized: true
+tracksRegLiveness: true
+
+body: |
+  bb.0:
+    liveins: $sgpr0, $vgpr0
+
+    ; CHECK-LABEL: name: reg_sequence_sv_vreg
+    ; CHECK: liveins: $sgpr0, $vgpr0
+    ; CHECK: [[COPY:%[0-9]+]]:sgpr(s32) = COPY $sgpr0
+    ; CHECK: [[COPY1:%[0-9]+]]:vgpr(s32) = COPY $vgpr0
+    ; CHECK: [[REG_SEQUENCE:%[0-9]+]]:sgpr(s64) = REG_SEQUENCE [[COPY]](s32), %subreg.sub0, [[COPY1]](s32), %subreg.sub1
+    %0:_(s32) = COPY $sgpr0
+    %1:_(s32) = COPY $vgpr0
+    %2:_(s64) = REG_SEQUENCE %0, %subreg.sub0, %1, %subreg.sub1
+...
+
+---
+name: reg_sequence_sv_physreg
+legalized: true
+tracksRegLiveness: true
+
+body: |
+  bb.0:
+    liveins: $sgpr0, $vgpr0
+
+    ; CHECK-LABEL: name: reg_sequence_sv_physreg
+    ; CHECK: liveins: $sgpr0, $vgpr0
+    ; CHECK: [[REG_SEQUENCE:%[0-9]+]]:sgpr(s64) = REG_SEQUENCE $sgpr0, %subreg.sub0, $vgpr0, %subreg.sub1
+    %0:_(s64) = REG_SEQUENCE $sgpr0, %subreg.sub0, $vgpr0, %subreg.sub1
+...
+
+---
+name: reg_sequence_vs_vreg
+legalized: true
+tracksRegLiveness: true
+
+body: |
+  bb.0:
+    liveins: $vgpr0, $sgpr0
+
+    ; CHECK-LABEL: name: reg_sequence_vs_vreg
+    ; CHECK: liveins: $vgpr0, $sgpr0
+    ; CHECK: [[COPY:%[0-9]+]]:vgpr(s32) = COPY $vgpr0
+    ; CHECK: [[COPY1:%[0-9]+]]:sgpr(s32) = COPY $sgpr0
+    ; CHECK: [[REG_SEQUENCE:%[0-9]+]]:vgpr(s64) = REG_SEQUENCE [[COPY]](s32), %subreg.sub0, [[COPY1]](s32), %subreg.sub1
+    %0:_(s32) = COPY $vgpr0
+    %1:_(s32) = COPY $sgpr0
+    %2:_(s64) = REG_SEQUENCE %0, %subreg.sub0, %1, %subreg.sub1
+...
+
+---
+name: reg_sequence_vs_physreg
+legalized: true
+tracksRegLiveness: true
+
+body: |
+  bb.0:
+    liveins: $vgpr0, $sgpr0
+
+    ; CHECK-LABEL: name: reg_sequence_vs_physreg
+    ; CHECK: liveins: $vgpr0, $sgpr0
+    ; CHECK: [[REG_SEQUENCE:%[0-9]+]]:vgpr(s64) = REG_SEQUENCE $vgpr0, %subreg.sub0, $sgpr0, %subreg.sub1
+    %0:_(s64) = REG_SEQUENCE $vgpr0, %subreg.sub0, $sgpr0, %subreg.sub1
+...
+
+---
+name: reg_sequence_vv_vreg
+legalized: true
+tracksRegLiveness: true
+
+body: |
+  bb.0:
+    liveins: $vgpr0, $vgpr1
+
+    ; CHECK-LABEL: name: reg_sequence_vv_vreg
+    ; CHECK: liveins: $vgpr0, $vgpr1
+    ; CHECK: [[COPY:%[0-9]+]]:vgpr(s32) = COPY $vgpr0
+    ; CHECK: [[COPY1:%[0-9]+]]:vgpr(s32) = COPY $vgpr1
+    ; CHECK: [[REG_SEQUENCE:%[0-9]+]]:vgpr(s64) = REG_SEQUENCE [[COPY]](s32), %subreg.sub0, [[COPY1]](s32), %subreg.sub1
+    %0:_(s32) = COPY $vgpr0
+    %1:_(s32) = COPY $vgpr1
+    %2:_(s64) = REG_SEQUENCE %0, %subreg.sub0, %1, %subreg.sub1
+...
+
+---
+name: reg_sequence_vv_physreg
+legalized: true
+tracksRegLiveness: true
+
+body: |
+  bb.0:
+    liveins: $vgpr0, $vgpr1
+
+    ; CHECK-LABEL: name: reg_sequence_vv_physreg
+    ; CHECK: liveins: $vgpr0, $vgpr1
+    ; CHECK: [[REG_SEQUENCE:%[0-9]+]]:vgpr(s64) = REG_SEQUENCE $vgpr0, %subreg.sub0, $vgpr1, %subreg.sub1
+    %0:_(s64) = REG_SEQUENCE $vgpr0, %subreg.sub0, $vgpr1, %subreg.sub1
+...
+