Index: lib/CodeGen/GlobalISel/LegalizerHelper.cpp
===================================================================
--- lib/CodeGen/GlobalISel/LegalizerHelper.cpp
+++ lib/CodeGen/GlobalISel/LegalizerHelper.cpp
@@ -1098,6 +1098,32 @@
   }
 
   const unsigned WideSize = WideTy.getSizeInBits();
+  if (SrcTy != WideTy) {
+    // Try to unmerge to an intermediate type to avoid creating a wide, illegal
+    // shiift.
+
+    LLT GCDTy = getGCDType(SrcTy, WideTy);
+    if (GCDTy != DstTy && SrcTy != GCDTy &&
+        GCDTy.getSizeInBits() >= DstTy.getSizeInBits()) {
+      auto Unmerge = MIRBuilder.buildUnmerge(GCDTy, SrcReg);
+      const int NumUnmerge = Unmerge->getNumOperands() - 1;
+      const int PartsPerUnmerge = NumDst / NumUnmerge;
+
+      assert(NumUnmerge > 1 && PartsPerUnmerge > 1);
+
+      for (int I = 0; I != NumUnmerge; ++I) {
+        auto MIB = MIRBuilder.buildInstr(TargetOpcode::G_UNMERGE_VALUES);
+
+        for (int J = 0; J != PartsPerUnmerge; ++J)
+          MIB.addDef(MI.getOperand(I * PartsPerUnmerge + J).getReg());
+        MIB.addUse(Unmerge.getReg(I));
+      }
+
+      MI.eraseFromParent();
+      return Legalized;
+    }
+  }
+
   unsigned NewSrcSize = NumDst * WideSize;
   LLT NewSrcTy = LLT::scalar(NewSrcSize);
   unsigned SizeDiff = WideSize - DstTy.getSizeInBits();
Index: test/CodeGen/AMDGPU/GlobalISel/legalize-unmerge-values.mir
===================================================================
--- test/CodeGen/AMDGPU/GlobalISel/legalize-unmerge-values.mir
+++ test/CodeGen/AMDGPU/GlobalISel/legalize-unmerge-values.mir
@@ -175,28 +175,20 @@
     liveins: $vgpr0
     ; CHECK-LABEL: name: test_unmerge_s8_s32
     ; CHECK: [[COPY:%[0-9]+]]:_(s32) = COPY $vgpr0
-    ; CHECK: [[ZEXT:%[0-9]+]]:_(s64) = G_ZEXT [[COPY]](s32)
-    ; CHECK: [[C:%[0-9]+]]:_(s64) = G_CONSTANT i64 8
-    ; CHECK: [[TRUNC:%[0-9]+]]:_(s32) = G_TRUNC [[C]](s64)
-    ; CHECK: [[SHL:%[0-9]+]]:_(s64) = G_SHL [[ZEXT]], [[TRUNC]](s32)
-    ; CHECK: [[OR:%[0-9]+]]:_(s64) = G_OR [[ZEXT]], [[SHL]]
-    ; CHECK: [[C1:%[0-9]+]]:_(s64) = G_CONSTANT i64 16
-    ; CHECK: [[TRUNC1:%[0-9]+]]:_(s32) = G_TRUNC [[C1]](s64)
-    ; CHECK: [[SHL1:%[0-9]+]]:_(s64) = G_SHL [[OR]], [[TRUNC1]](s32)
-    ; CHECK: [[OR1:%[0-9]+]]:_(s64) = G_OR [[OR]], [[SHL1]]
-    ; CHECK: [[C2:%[0-9]+]]:_(s64) = G_CONSTANT i64 24
-    ; CHECK: [[TRUNC2:%[0-9]+]]:_(s32) = G_TRUNC [[C2]](s64)
-    ; CHECK: [[SHL2:%[0-9]+]]:_(s64) = G_SHL [[OR1]], [[TRUNC2]](s32)
-    ; CHECK: [[OR2:%[0-9]+]]:_(s64) = G_OR [[OR1]], [[SHL2]]
-    ; CHECK: [[UV:%[0-9]+]]:_(s16), [[UV1:%[0-9]+]]:_(s16), [[UV2:%[0-9]+]]:_(s16), [[UV3:%[0-9]+]]:_(s16) = G_UNMERGE_VALUES [[OR2]](s64)
+    ; CHECK: [[UV:%[0-9]+]]:_(s16), [[UV1:%[0-9]+]]:_(s16) = G_UNMERGE_VALUES [[COPY]](s32)
     ; CHECK: [[ANYEXT:%[0-9]+]]:_(s32) = G_ANYEXT [[UV]](s16)
+    ; CHECK: [[C:%[0-9]+]]:_(s32) = G_CONSTANT i32 8
+    ; CHECK: [[LSHR:%[0-9]+]]:_(s32) = G_LSHR [[ANYEXT]], [[C]](s32)
     ; CHECK: [[ANYEXT1:%[0-9]+]]:_(s32) = G_ANYEXT [[UV1]](s16)
-    ; CHECK: [[ANYEXT2:%[0-9]+]]:_(s32) = G_ANYEXT [[UV2]](s16)
-    ; CHECK: [[ANYEXT3:%[0-9]+]]:_(s32) = G_ANYEXT [[UV3]](s16)
-    ; CHECK: $vgpr0 = COPY [[ANYEXT]](s32)
-    ; CHECK: $vgpr1 = COPY [[ANYEXT1]](s32)
-    ; CHECK: $vgpr2 = COPY [[ANYEXT2]](s32)
-    ; CHECK: $vgpr3 = COPY [[ANYEXT3]](s32)
+    ; CHECK: [[LSHR1:%[0-9]+]]:_(s32) = G_LSHR [[ANYEXT1]], [[C]](s32)
+    ; CHECK: [[COPY1:%[0-9]+]]:_(s32) = COPY [[ANYEXT]](s32)
+    ; CHECK: [[COPY2:%[0-9]+]]:_(s32) = COPY [[LSHR]](s32)
+    ; CHECK: [[COPY3:%[0-9]+]]:_(s32) = COPY [[ANYEXT1]](s32)
+    ; CHECK: [[COPY4:%[0-9]+]]:_(s32) = COPY [[LSHR1]](s32)
+    ; CHECK: $vgpr0 = COPY [[COPY1]](s32)
+    ; CHECK: $vgpr1 = COPY [[COPY2]](s32)
+    ; CHECK: $vgpr2 = COPY [[COPY3]](s32)
+    ; CHECK: $vgpr3 = COPY [[COPY4]](s32)
     %0:_(s32) = COPY $vgpr0
     %1:_(s8), %2:_(s8), %3:_(s8), %4:_(s8) = G_UNMERGE_VALUES %0
     %5:_(s32) = G_ANYEXT %1
@@ -209,6 +201,148 @@
     $vgpr3 = COPY %8
 ...
 
+---
+name: test_unmerge_s8_s48
+body: |
+  bb.0:
+    liveins: $vgpr0_vgpr1
+    ; CHECK-LABEL: name: test_unmerge_s8_s48
+    ; CHECK: [[COPY:%[0-9]+]]:_(s64) = COPY $vgpr0_vgpr1
+    ; CHECK: [[TRUNC:%[0-9]+]]:_(s48) = G_TRUNC [[COPY]](s64)
+    ; CHECK: [[UV:%[0-9]+]]:_(s16), [[UV1:%[0-9]+]]:_(s16), [[UV2:%[0-9]+]]:_(s16) = G_UNMERGE_VALUES [[TRUNC]](s48)
+    ; CHECK: [[ANYEXT:%[0-9]+]]:_(s32) = G_ANYEXT [[UV]](s16)
+    ; CHECK: [[C:%[0-9]+]]:_(s32) = G_CONSTANT i32 8
+    ; CHECK: [[LSHR:%[0-9]+]]:_(s32) = G_LSHR [[ANYEXT]], [[C]](s32)
+    ; CHECK: [[ANYEXT1:%[0-9]+]]:_(s32) = G_ANYEXT [[UV1]](s16)
+    ; CHECK: [[LSHR1:%[0-9]+]]:_(s32) = G_LSHR [[ANYEXT1]], [[C]](s32)
+    ; CHECK: [[ANYEXT2:%[0-9]+]]:_(s32) = G_ANYEXT [[UV2]](s16)
+    ; CHECK: [[LSHR2:%[0-9]+]]:_(s32) = G_LSHR [[ANYEXT2]], [[C]](s32)
+    ; CHECK: [[COPY1:%[0-9]+]]:_(s32) = COPY [[ANYEXT]](s32)
+    ; CHECK: [[COPY2:%[0-9]+]]:_(s32) = COPY [[LSHR]](s32)
+    ; CHECK: [[COPY3:%[0-9]+]]:_(s32) = COPY [[ANYEXT1]](s32)
+    ; CHECK: [[COPY4:%[0-9]+]]:_(s32) = COPY [[LSHR1]](s32)
+    ; CHECK: [[COPY5:%[0-9]+]]:_(s32) = COPY [[ANYEXT2]](s32)
+    ; CHECK: [[COPY6:%[0-9]+]]:_(s32) = COPY [[LSHR2]](s32)
+    ; CHECK: $vgpr0 = COPY [[COPY1]](s32)
+    ; CHECK: $vgpr1 = COPY [[COPY2]](s32)
+    ; CHECK: $vgpr2 = COPY [[COPY3]](s32)
+    ; CHECK: $vgpr3 = COPY [[COPY4]](s32)
+    ; CHECK: $vgpr4 = COPY [[COPY5]](s32)
+    ; CHECK: $vgpr5 = COPY [[COPY6]](s32)
+    %0:_(s64) = COPY $vgpr0_vgpr1
+    %1:_(s48) = G_TRUNC %0
+    %2:_(s8), %3:_(s8), %4:_(s8), %5:_(s8), %6:_(s8), %7:_(s8) = G_UNMERGE_VALUES %1
+    %8:_(s32) = G_ANYEXT %2
+    %9:_(s32) = G_ANYEXT %3
+    %10:_(s32) = G_ANYEXT %4
+    %11:_(s32) = G_ANYEXT %5
+    %12:_(s32) = G_ANYEXT %6
+    %13:_(s32) = G_ANYEXT %7
+    $vgpr0 = COPY %8
+    $vgpr1 = COPY %9
+    $vgpr2 = COPY %10
+    $vgpr3 = COPY %11
+    $vgpr4 = COPY %12
+    $vgpr5 = COPY %13
+...
+
+---
+name: test_unmerge_s8_s64
+body: |
+  bb.0:
+    liveins: $vgpr0_vgpr1
+    ; CHECK-LABEL: name: test_unmerge_s8_s64
+    ; CHECK: [[COPY:%[0-9]+]]:_(s64) = COPY $vgpr0_vgpr1
+    ; CHECK: [[UV:%[0-9]+]]:_(s16), [[UV1:%[0-9]+]]:_(s16), [[UV2:%[0-9]+]]:_(s16), [[UV3:%[0-9]+]]:_(s16) = G_UNMERGE_VALUES [[COPY]](s64)
+    ; CHECK: [[ANYEXT:%[0-9]+]]:_(s32) = G_ANYEXT [[UV]](s16)
+    ; CHECK: [[C:%[0-9]+]]:_(s32) = G_CONSTANT i32 8
+    ; CHECK: [[LSHR:%[0-9]+]]:_(s32) = G_LSHR [[ANYEXT]], [[C]](s32)
+    ; CHECK: [[ANYEXT1:%[0-9]+]]:_(s32) = G_ANYEXT [[UV1]](s16)
+    ; CHECK: [[LSHR1:%[0-9]+]]:_(s32) = G_LSHR [[ANYEXT1]], [[C]](s32)
+    ; CHECK: [[ANYEXT2:%[0-9]+]]:_(s32) = G_ANYEXT [[UV2]](s16)
+    ; CHECK: [[LSHR2:%[0-9]+]]:_(s32) = G_LSHR [[ANYEXT2]], [[C]](s32)
+    ; CHECK: [[ANYEXT3:%[0-9]+]]:_(s32) = G_ANYEXT [[UV3]](s16)
+    ; CHECK: [[LSHR3:%[0-9]+]]:_(s32) = G_LSHR [[ANYEXT3]], [[C]](s32)
+    ; CHECK: [[COPY1:%[0-9]+]]:_(s32) = COPY [[ANYEXT]](s32)
+    ; CHECK: [[COPY2:%[0-9]+]]:_(s32) = COPY [[LSHR]](s32)
+    ; CHECK: [[COPY3:%[0-9]+]]:_(s32) = COPY [[ANYEXT1]](s32)
+    ; CHECK: [[COPY4:%[0-9]+]]:_(s32) = COPY [[LSHR1]](s32)
+    ; CHECK: [[COPY5:%[0-9]+]]:_(s32) = COPY [[ANYEXT2]](s32)
+    ; CHECK: [[COPY6:%[0-9]+]]:_(s32) = COPY [[LSHR2]](s32)
+    ; CHECK: [[COPY7:%[0-9]+]]:_(s32) = COPY [[ANYEXT3]](s32)
+    ; CHECK: [[COPY8:%[0-9]+]]:_(s32) = COPY [[LSHR3]](s32)
+    ; CHECK: $vgpr0 = COPY [[COPY1]](s32)
+    ; CHECK: $vgpr1 = COPY [[COPY2]](s32)
+    ; CHECK: $vgpr2 = COPY [[COPY3]](s32)
+    ; CHECK: $vgpr3 = COPY [[COPY4]](s32)
+    ; CHECK: $vgpr4 = COPY [[COPY5]](s32)
+    ; CHECK: $vgpr5 = COPY [[COPY6]](s32)
+    ; CHECK: $vgpr6 = COPY [[COPY7]](s32)
+    ; CHECK: $vgpr7 = COPY [[COPY8]](s32)
+    %0:_(s64) = COPY $vgpr0_vgpr1
+    %1:_(s8), %2:_(s8), %3:_(s8), %4:_(s8), %5:_(s8), %6:_(s8), %7:_(s8), %8:_(s8) = G_UNMERGE_VALUES %0
+    %10:_(s32) = G_ANYEXT %1
+    %11:_(s32) = G_ANYEXT %2
+    %12:_(s32) = G_ANYEXT %3
+    %13:_(s32) = G_ANYEXT %4
+    %14:_(s32) = G_ANYEXT %5
+    %15:_(s32) = G_ANYEXT %6
+    %16:_(s32) = G_ANYEXT %7
+    %17:_(s32) = G_ANYEXT %8
+    $vgpr0 = COPY %10
+    $vgpr1 = COPY %11
+    $vgpr2 = COPY %12
+    $vgpr3 = COPY %13
+    $vgpr4 = COPY %14
+    $vgpr5 = COPY %15
+    $vgpr6 = COPY %16
+    $vgpr7 = COPY %17
+...
+
+---
+name: test_unmerge_s8_p1
+body: |
+  bb.0:
+    liveins: $vgpr0_vgpr1
+    ; CHECK-LABEL: name: test_unmerge_s8_p1
+    ; CHECK: [[COPY:%[0-9]+]]:_(p1) = COPY $vgpr0_vgpr1
+    ; CHECK: [[UV:%[0-9]+]]:_(s8), [[UV1:%[0-9]+]]:_(s8), [[UV2:%[0-9]+]]:_(s8), [[UV3:%[0-9]+]]:_(s8), [[UV4:%[0-9]+]]:_(s8), [[UV5:%[0-9]+]]:_(s8), [[UV6:%[0-9]+]]:_(s8), [[UV7:%[0-9]+]]:_(s8) = G_UNMERGE_VALUES [[COPY]](p1)
+    ; CHECK: [[ANYEXT:%[0-9]+]]:_(s32) = G_ANYEXT [[UV]](s8)
+    ; CHECK: [[ANYEXT1:%[0-9]+]]:_(s32) = G_ANYEXT [[UV1]](s8)
+    ; CHECK: [[ANYEXT2:%[0-9]+]]:_(s32) = G_ANYEXT [[UV2]](s8)
+    ; CHECK: [[ANYEXT3:%[0-9]+]]:_(s32) = G_ANYEXT [[UV3]](s8)
+    ; CHECK: [[ANYEXT4:%[0-9]+]]:_(s32) = G_ANYEXT [[UV4]](s8)
+    ; CHECK: [[ANYEXT5:%[0-9]+]]:_(s32) = G_ANYEXT [[UV5]](s8)
+    ; CHECK: [[ANYEXT6:%[0-9]+]]:_(s32) = G_ANYEXT [[UV6]](s8)
+    ; CHECK: [[ANYEXT7:%[0-9]+]]:_(s32) = G_ANYEXT [[UV7]](s8)
+    ; CHECK: $vgpr0 = COPY [[ANYEXT]](s32)
+    ; CHECK: $vgpr1 = COPY [[ANYEXT1]](s32)
+    ; CHECK: $vgpr2 = COPY [[ANYEXT2]](s32)
+    ; CHECK: $vgpr3 = COPY [[ANYEXT3]](s32)
+    ; CHECK: $vgpr4 = COPY [[ANYEXT4]](s32)
+    ; CHECK: $vgpr5 = COPY [[ANYEXT5]](s32)
+    ; CHECK: $vgpr6 = COPY [[ANYEXT6]](s32)
+    ; CHECK: $vgpr7 = COPY [[ANYEXT7]](s32)
+    %0:_(p1) = COPY $vgpr0_vgpr1
+    %1:_(s8), %2:_(s8), %3:_(s8), %4:_(s8), %5:_(s8), %6:_(s8), %7:_(s8), %8:_(s8) = G_UNMERGE_VALUES %0
+    %10:_(s32) = G_ANYEXT %1
+    %11:_(s32) = G_ANYEXT %2
+    %12:_(s32) = G_ANYEXT %3
+    %13:_(s32) = G_ANYEXT %4
+    %14:_(s32) = G_ANYEXT %5
+    %15:_(s32) = G_ANYEXT %6
+    %16:_(s32) = G_ANYEXT %7
+    %17:_(s32) = G_ANYEXT %8
+    $vgpr0 = COPY %10
+    $vgpr1 = COPY %11
+    $vgpr2 = COPY %12
+    $vgpr3 = COPY %13
+    $vgpr4 = COPY %14
+    $vgpr5 = COPY %15
+    $vgpr6 = COPY %16
+    $vgpr7 = COPY %17
+...
+
 ---
 name: test_unmerge_s16_s32
 body: |