Index: llvm/lib/Target/AMDGPU/AMDGPUInstructionSelector.cpp
===================================================================
--- llvm/lib/Target/AMDGPU/AMDGPUInstructionSelector.cpp
+++ llvm/lib/Target/AMDGPU/AMDGPUInstructionSelector.cpp
@@ -1852,12 +1852,33 @@
   if (!DstTy.isScalar())
     return false;
 
-  if (I.getOpcode() == AMDGPU::G_ANYEXT)
-    return selectCOPY(I);
-
   // Artifact casts should never use vcc.
   const RegisterBank *SrcBank = getArtifactRegBank(SrcReg, *MRI, TRI);
 
+  // FIXME: This should probably be illegal and split earlier.
+  if (I.getOpcode() == AMDGPU::G_ANYEXT) {
+    if (DstSize <= 32)
+      return selectCOPY(I);
+
+    const TargetRegisterClass *SrcRC =
+        TRI.getRegClassForTypeOnBank(SrcTy, *SrcBank, *MRI);
+    const RegisterBank *DstBank = RBI.getRegBank(DstReg, *MRI, TRI);
+    const TargetRegisterClass *DstRC =
+        TRI.getRegClassForSizeOnBank(DstSize, *DstBank, *MRI);
+
+    Register UndefReg = MRI->createVirtualRegister(SrcRC);
+    BuildMI(MBB, I, DL, TII.get(AMDGPU::IMPLICIT_DEF), UndefReg);
+    BuildMI(MBB, I, DL, TII.get(AMDGPU::REG_SEQUENCE), DstReg)
+      .addReg(SrcReg)
+      .addImm(AMDGPU::sub0)
+      .addReg(UndefReg)
+      .addImm(AMDGPU::sub1);
+    I.eraseFromParent();
+
+    return RBI.constrainGenericRegister(DstReg, *DstRC, *MRI) &&
+           RBI.constrainGenericRegister(SrcReg, *SrcRC, *MRI);
+  }
+
   if (SrcBank->getID() == AMDGPU::VGPRRegBankID && DstSize <= 32) {
     // 64-bit should have been split up in RegBankSelect
 
Index: llvm/test/CodeGen/AMDGPU/GlobalISel/inst-select-anyext.mir
===================================================================
--- llvm/test/CodeGen/AMDGPU/GlobalISel/inst-select-anyext.mir
+++ llvm/test/CodeGen/AMDGPU/GlobalISel/inst-select-anyext.mir
@@ -22,22 +22,88 @@
 ...
 
 ---
+name:  anyext_sgpr_s32_to_sgpr_s64
+legalized:       true
+regBankSelected: true
+tracksRegLiveness: true
+body:             |
+  bb.0:
+    liveins: $sgpr0
+
+    ; GCN-LABEL: name: anyext_sgpr_s32_to_sgpr_s64
+    ; GCN: liveins: $sgpr0
+    ; GCN: [[COPY:%[0-9]+]]:sreg_32 = COPY $sgpr0
+    ; GCN: [[DEF:%[0-9]+]]:sreg_32 = IMPLICIT_DEF
+    ; GCN: [[REG_SEQUENCE:%[0-9]+]]:sreg_64 = REG_SEQUENCE [[COPY]], %subreg.sub0, [[DEF]], %subreg.sub1
+    ; GCN: S_ENDPGM 0, implicit [[REG_SEQUENCE]]
+    %0:sgpr(s32) = COPY $sgpr0
+    %1:sgpr(s64) = G_ANYEXT %0
+    S_ENDPGM 0, implicit %1
+
+...
 
-name: anyext_sgpr_s16_to_sgpr_s64
+---
+name:  anyext_sgpr_s16_to_sgpr_s64
 legalized:       true
 regBankSelected: true
-body: |
+tracksRegLiveness: true
+body:             |
   bb.0:
     liveins: $sgpr0
 
     ; GCN-LABEL: name: anyext_sgpr_s16_to_sgpr_s64
+    ; GCN: liveins: $sgpr0
     ; GCN: [[COPY:%[0-9]+]]:sreg_32 = COPY $sgpr0
-    ; GCN: [[COPY1:%[0-9]+]]:sreg_64 = COPY [[COPY]]
-    ; GCN: $sgpr0_sgpr1 = COPY [[COPY1]]
+    ; GCN: [[DEF:%[0-9]+]]:sreg_32 = IMPLICIT_DEF
+    ; GCN: [[REG_SEQUENCE:%[0-9]+]]:sreg_64 = REG_SEQUENCE [[COPY]], %subreg.sub0, [[DEF]], %subreg.sub1
+    ; GCN: S_ENDPGM 0, implicit [[REG_SEQUENCE]]
     %0:sgpr(s32) = COPY $sgpr0
     %1:sgpr(s16) = G_TRUNC %0
     %2:sgpr(s64) = G_ANYEXT %1
-    $sgpr0_sgpr1 = COPY %2
+    S_ENDPGM 0, implicit %2
+
+...
+
+---
+name:  anyext_vgpr_s32_to_vgpr_s64
+legalized:       true
+regBankSelected: true
+tracksRegLiveness: true
+body:             |
+  bb.0:
+    liveins: $vgpr0
+
+    ; GCN-LABEL: name: anyext_vgpr_s32_to_vgpr_s64
+    ; GCN: liveins: $vgpr0
+    ; GCN: [[COPY:%[0-9]+]]:vgpr_32 = COPY $vgpr0
+    ; GCN: [[DEF:%[0-9]+]]:vgpr_32 = IMPLICIT_DEF
+    ; GCN: [[REG_SEQUENCE:%[0-9]+]]:vreg_64 = REG_SEQUENCE [[COPY]], %subreg.sub0, [[DEF]], %subreg.sub1
+    ; GCN: S_ENDPGM 0, implicit [[REG_SEQUENCE]]
+    %0:vgpr(s32) = COPY $vgpr0
+    %1:vgpr(s64) = G_ANYEXT %0
+    S_ENDPGM 0, implicit %1
+
+...
+
+---
+name:  anyext_vgpr_s16_to_vgpr_s64
+legalized:       true
+regBankSelected: true
+tracksRegLiveness: true
+body:             |
+  bb.0:
+    liveins: $vgpr0
+
+    ; GCN-LABEL: name: anyext_vgpr_s16_to_vgpr_s64
+    ; GCN: liveins: $vgpr0
+    ; GCN: [[COPY:%[0-9]+]]:vgpr_32 = COPY $vgpr0
+    ; GCN: [[DEF:%[0-9]+]]:vgpr_32 = IMPLICIT_DEF
+    ; GCN: [[REG_SEQUENCE:%[0-9]+]]:vreg_64 = REG_SEQUENCE [[COPY]], %subreg.sub0, [[DEF]], %subreg.sub1
+    ; GCN: S_ENDPGM 0, implicit [[REG_SEQUENCE]]
+    %0:vgpr(s32) = COPY $vgpr0
+    %1:vgpr(s16) = G_TRUNC %0
+    %2:vgpr(s64) = G_ANYEXT %1
+    S_ENDPGM 0, implicit %2
 
 ...