Index: lib/CodeGen/SelectionDAG/DAGCombiner.cpp
===================================================================
--- lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -14035,6 +14035,11 @@
         // when we start sorting the vectors by type.
         return SDValue();
       }
+    } else if (InVT2.getSizeInBits() * 2 == VT.getSizeInBits() &&
+               InVT1.getSizeInBits() == VT.getSizeInBits()) {
+      SmallVector<SDValue, 2> ConcatOps(2, DAG.getUNDEF(InVT2));
+      ConcatOps[0] = VecIn2;
+      VecIn2 = DAG.getNode(ISD::CONCAT_VECTORS, DL, VT, ConcatOps);
     } else {
       // TODO: Support cases where the length mismatch isn't exactly by a
       // factor of 2.
Index: test/CodeGen/AArch64/arm64-neon-copy.ll
===================================================================
--- test/CodeGen/AArch64/arm64-neon-copy.ll
+++ test/CodeGen/AArch64/arm64-neon-copy.ll
@@ -1378,7 +1378,7 @@
 
 define <2 x i64> @test_concat_v2i64_v2i64_v1i64(<2 x i64> %x, <1 x i64> %y) #0 {
 ; CHECK-LABEL: test_concat_v2i64_v2i64_v1i64:
-; CHECK: ins {{v[0-9]+}}.d[1], {{v[0-9]+}}.d[0]
+; CHECK: zip1 {{v[0-9]+}}.2d, {{v[0-9]+}}.2d, {{v[0-9]+}}.2d
 entry:
   %vecext = extractelement <2 x i64> %x, i32 0
   %vecinit = insertelement <2 x i64> undef, i64 %vecext, i32 0
Index: test/CodeGen/X86/vector-shuffle-v48.ll
===================================================================
--- test/CodeGen/X86/vector-shuffle-v48.ll
+++ test/CodeGen/X86/vector-shuffle-v48.ll
@@ -3,42 +3,18 @@
 define <32 x i8> @foo(<48 x i8>* %x0, <16 x i32> %x1, <16 x i32> %x2) {
 ; CHECK-LABEL: foo:
 ; CHECK:       # BB#0:
-; CHECK-NEXT:    vmovdqu 32(%rdi), %xmm0
-; CHECK-NEXT:    vmovdqu (%rdi), %ymm1
-; CHECK-NEXT:    vextracti128 $1, %ymm1, %xmm2
-; CHECK-NEXT:    vpextrb $0, %xmm2, %eax
-; CHECK-NEXT:    vpshufb {{.*#+}} xmm1 = xmm1[0,1,3,4,6,7,9,10,12,13,15],zero,zero,zero,zero,zero
-; CHECK-NEXT:    vpinsrb $11, %eax, %xmm1, %xmm1
-; CHECK-NEXT:    vpextrb $2, %xmm2, %eax
-; CHECK-NEXT:    vpinsrb $12, %eax, %xmm1, %xmm1
-; CHECK-NEXT:    vpextrb $3, %xmm2, %eax
-; CHECK-NEXT:    vpinsrb $13, %eax, %xmm1, %xmm1
-; CHECK-NEXT:    vpextrb $5, %xmm2, %eax
-; CHECK-NEXT:    vpinsrb $14, %eax, %xmm1, %xmm1
-; CHECK-NEXT:    vpextrb $6, %xmm2, %eax
-; CHECK-NEXT:    vpinsrb $15, %eax, %xmm1, %xmm1
-; CHECK-NEXT:    vpextrb $1, %xmm0, %eax
-; CHECK-NEXT:    vpshufb {{.*#+}} xmm2 = xmm2[8,9,11,12,14,15],zero,zero,zero,zero,zero,zero,zero,zero,zero,zero
-; CHECK-NEXT:    vpinsrb $6, %eax, %xmm2, %xmm2
-; CHECK-NEXT:    vpextrb $2, %xmm0, %eax
-; CHECK-NEXT:    vpinsrb $7, %eax, %xmm2, %xmm2
-; CHECK-NEXT:    vpextrb $4, %xmm0, %eax
-; CHECK-NEXT:    vpinsrb $8, %eax, %xmm2, %xmm2
-; CHECK-NEXT:    vpextrb $5, %xmm0, %eax
-; CHECK-NEXT:    vpinsrb $9, %eax, %xmm2, %xmm2
-; CHECK-NEXT:    vpextrb $7, %xmm0, %eax
-; CHECK-NEXT:    vpinsrb $10, %eax, %xmm2, %xmm2
-; CHECK-NEXT:    vpextrb $8, %xmm0, %eax
-; CHECK-NEXT:    vpinsrb $11, %eax, %xmm2, %xmm2
-; CHECK-NEXT:    vpextrb $10, %xmm0, %eax
-; CHECK-NEXT:    vpinsrb $12, %eax, %xmm2, %xmm2
-; CHECK-NEXT:    vpextrb $11, %xmm0, %eax
-; CHECK-NEXT:    vpinsrb $13, %eax, %xmm2, %xmm2
-; CHECK-NEXT:    vpextrb $13, %xmm0, %eax
-; CHECK-NEXT:    vpinsrb $14, %eax, %xmm2, %xmm2
-; CHECK-NEXT:    vpextrb $14, %xmm0, %eax
-; CHECK-NEXT:    vpinsrb $15, %eax, %xmm2, %xmm0
-; CHECK-NEXT:    vinserti128 $1, %xmm0, %ymm1, %ymm0
+; CHECK-NEXT:    vmovdqu (%rdi), %ymm0
+; CHECK-NEXT:    vmovdqu 32(%rdi), %xmm1
+; CHECK-NEXT:    vpshufb {{.*#+}} xmm1 = xmm1[u,u,u,u,u,u,1,2,4,5,7,8,10,11,13,14]
+; CHECK-NEXT:    vinserti128 $1, %xmm1, %ymm0, %ymm1
+; CHECK-NEXT:    vextracti128 $1, %ymm0, %xmm2
+; CHECK-NEXT:    vpshufb {{.*#+}} xmm3 = zero,zero,zero,zero,zero,zero,zero,zero,zero,zero,zero,xmm2[0,2,3,5,6]
+; CHECK-NEXT:    vpshufb {{.*#+}} xmm0 = xmm0[0,1,3,4,6,7,9,10,12,13,15],zero,zero,zero,zero,zero
+; CHECK-NEXT:    vpor %xmm3, %xmm0, %xmm0
+; CHECK-NEXT:    vpshufb {{.*#+}} xmm2 = xmm2[8,9,11,12,14,15,u,u,u,u,u,u,u,u,u,u]
+; CHECK-NEXT:    vinserti128 $1, %xmm2, %ymm0, %ymm0
+; CHECK-NEXT:    vmovdqa {{.*#+}} ymm2 = [255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,0,0,0,0,0,0,0,0,0,0]
+; CHECK-NEXT:    vpblendvb %ymm2, %ymm0, %ymm1, %ymm0
 ; CHECK-NEXT:    retq
   %1 = load <48 x i8>, <48 x i8>* %x0, align 1
   %2 = shufflevector <48 x i8> %1, <48 x i8> undef, <32 x i32> <i32 0, i32 1, i32 3, i32 4, i32 6, i32 7, i32 9, i32 10, i32 12, i32 13, i32 15, i32 16, i32 18, i32 19, i32 21, i32 22, i32 24, i32 25, i32 27, i32 28, i32 30, i32 31, i32 33, i32 34, i32 36, i32 37, i32 39, i32 40, i32 42, i32 43, i32 45, i32 46>