Index: lib/CodeGen/SelectionDAG/DAGCombiner.cpp
===================================================================
--- lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -18326,6 +18326,43 @@
 
   unsigned InsIdx = cast<ConstantSDNode>(N2)->getZExtValue();
 
+  // Push subvector bitcasts to the output, adjusting the index as we go.
+  // insert_subvector(bitcast(v), bitcast(s), c1)
+  // -> bitcast(insert_subvector(v,s,c2))
+  if ((N0.isUndef() || N0.getOpcode() == ISD::BITCAST) &&
+      N1.getOpcode() == ISD::BITCAST) {
+    SDValue N0Src = peekThroughBitcasts(N0);
+    SDValue N1Src = peekThroughBitcasts(N1);
+    EVT N0SrcSVT = N0Src.getValueType().getScalarType();
+    EVT N1SrcSVT = N1Src.getValueType().getScalarType();
+    if ((N0.isUndef() || N0SrcSVT == N1SrcSVT) &&
+        N0Src.getValueType().isVector() && N1Src.getValueType().isVector()) {
+      EVT NewVT;
+      SDLoc DL(N);
+      SDValue NewIdx;
+      MVT IdxVT = TLI.getVectorIdxTy(DAG.getDataLayout());
+      LLVMContext &Ctx = *DAG.getContext();
+      unsigned NumElts = VT.getVectorNumElements();
+      unsigned EltSizeInBits = VT.getScalarSizeInBits();
+      if ((EltSizeInBits % N1SrcSVT.getSizeInBits()) == 0) {
+        unsigned Scale = EltSizeInBits / N1SrcSVT.getSizeInBits();
+        NewVT = EVT::getVectorVT(Ctx, N1SrcSVT, NumElts * Scale);
+        NewIdx = DAG.getConstant(InsIdx * Scale, DL, IdxVT);
+      } else if ((N1SrcSVT.getSizeInBits() % EltSizeInBits) == 0) {
+        unsigned Scale = N1SrcSVT.getSizeInBits() / EltSizeInBits;
+        if ((InsIdx % Scale) == 0) {
+          NewVT = EVT::getVectorVT(Ctx, N1SrcSVT, NumElts / Scale);
+          NewIdx = DAG.getConstant(InsIdx / Scale, DL, IdxVT);
+        }
+      }
+      if (NewIdx && hasOperation(ISD::INSERT_SUBVECTOR, NewVT)) {
+        SDValue Res = DAG.getBitcast(NewVT, N0Src);
+        Res = DAG.getNode(ISD::INSERT_SUBVECTOR, DL, NewVT, Res, N1Src, NewIdx);
+        return DAG.getBitcast(VT, Res);
+      }
+    }
+  }
+
   // Canonicalize insert_subvector dag nodes.
   // Example:
   // (insert_subvector (insert_subvector A, Idx0), Idx1)
Index: lib/Target/X86/X86ISelLowering.cpp
===================================================================
--- lib/Target/X86/X86ISelLowering.cpp
+++ lib/Target/X86/X86ISelLowering.cpp
@@ -42231,42 +42231,6 @@
     }
   }
 
-  // Push subvector bitcasts to the output, adjusting the index as we go.
-  // insert_subvector(bitcast(v), bitcast(s), c1) ->
-  // bitcast(insert_subvector(v,s,c2))
-  // TODO: Move this to generic - which only supports same scalar sizes.
-  if ((Vec.isUndef() || Vec.getOpcode() == ISD::BITCAST) &&
-      SubVec.getOpcode() == ISD::BITCAST) {
-    SDValue VecSrc = peekThroughBitcasts(Vec);
-    SDValue SubVecSrc = peekThroughBitcasts(SubVec);
-    MVT VecSrcSVT = VecSrc.getSimpleValueType().getScalarType();
-    MVT SubVecSrcSVT = SubVecSrc.getSimpleValueType().getScalarType();
-    if (Vec.isUndef() || VecSrcSVT == SubVecSrcSVT) {
-      MVT NewOpVT;
-      SDValue NewIdx;
-      unsigned NumElts = OpVT.getVectorNumElements();
-      unsigned EltSizeInBits = OpVT.getScalarSizeInBits();
-      if ((EltSizeInBits % SubVecSrcSVT.getSizeInBits()) == 0) {
-        unsigned Scale = EltSizeInBits / SubVecSrcSVT.getSizeInBits();
-        NewOpVT = MVT::getVectorVT(SubVecSrcSVT, NumElts * Scale);
-        NewIdx = DAG.getIntPtrConstant(IdxVal * Scale, dl);
-      } else if ((SubVecSrcSVT.getSizeInBits() % EltSizeInBits) == 0) {
-        unsigned Scale = SubVecSrcSVT.getSizeInBits() / EltSizeInBits;
-        if ((IdxVal % Scale) == 0) {
-          NewOpVT = MVT::getVectorVT(SubVecSrcSVT, NumElts / Scale);
-          NewIdx = DAG.getIntPtrConstant(IdxVal / Scale, dl);
-        }
-      }
-      if (NewIdx && DAG.getTargetLoweringInfo().isOperationLegal(
-                        ISD::INSERT_SUBVECTOR, NewOpVT)) {
-        SDValue Res = DAG.getBitcast(NewOpVT, VecSrc);
-        Res = DAG.getNode(ISD::INSERT_SUBVECTOR, dl, NewOpVT, Res, SubVecSrc,
-                          NewIdx);
-        return DAG.getBitcast(OpVT, Res);
-      }
-    }
-  }
-
   // Match concat_vector style patterns.
   if ((IdxVal == OpVT.getVectorNumElements() / 2) &&
       Vec.getOpcode() == ISD::INSERT_SUBVECTOR &&