diff --git a/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp b/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
index d06a8b4..6b7f83f 100644
--- a/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
+++ b/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
@@ -171,6 +171,7 @@
   SDValue ExpandBitCount(unsigned Opc, SDValue Op, DebugLoc dl);
 
   SDValue ExpandExtractFromVectorThroughStack(SDValue Op);
+  SDValue ExpandInsertToVectorThroughStack(SDValue Op);
   SDValue ExpandVectorBuildThroughStack(SDNode* Node);
 
   std::pair<SDValue, SDValue> ExpandAtomic(SDNode *Node);
@@ -1588,6 +1589,50 @@
                         false, false, 0);
 }
 
+SDValue SelectionDAGLegalize::ExpandInsertToVectorThroughStack(SDValue Op) {
+  assert(Op.getValueType().isVector() && "Non-vector insert subvector!");
+
+  SDValue Vec  = Op.getOperand(0);
+  SDValue Part = Op.getOperand(1);
+  SDValue Idx  = Op.getOperand(2);
+  DebugLoc dl  = Op.getDebugLoc();
+
+  // Store the value to a temporary stack slot, then LOAD the returned part.
+
+  SDValue StackPtr = DAG.CreateStackTemporary(Vec.getValueType());
+  int FI = cast<FrameIndexSDNode>(StackPtr.getNode())->getIndex();
+  MachinePointerInfo PtrInfo = MachinePointerInfo::getFixedStack(FI);
+
+  // First store the whole vector.
+  SDValue Ch = DAG.getStore(DAG.getEntryNode(), dl, Vec, StackPtr, PtrInfo,
+                            false, false, 0);
+
+  // Then store the inserted part.
+
+  // Add the offset to the index.
+  unsigned EltSize =
+      Vec.getValueType().getVectorElementType().getSizeInBits()/8;
+
+  Idx = DAG.getNode(ISD::MUL, dl, Idx.getValueType(), Idx,
+                    DAG.getConstant(EltSize, Idx.getValueType()));
+
+  if (Idx.getValueType().bitsGT(TLI.getPointerTy()))
+    Idx = DAG.getNode(ISD::TRUNCATE, dl, TLI.getPointerTy(), Idx);
+  else
+    Idx = DAG.getNode(ISD::ZERO_EXTEND, dl, TLI.getPointerTy(), Idx);
+
+  SDValue SubStackPtr = DAG.getNode(ISD::ADD, dl, Idx.getValueType(), Idx,
+                                    StackPtr);
+
+  // Store the subvector.
+  Ch = DAG.getStore(DAG.getEntryNode(), dl, Part, SubStackPtr,
+                    MachinePointerInfo(), false, false, 0);
+
+  // Finally, load the updated vector.
+  return DAG.getLoad(Op.getValueType(), dl, Ch, StackPtr, PtrInfo,
+                     false, false, 0);
+}
+
 SDValue SelectionDAGLegalize::ExpandVectorBuildThroughStack(SDNode* Node) {
   // We can't handle this case efficiently.  Allocate a sufficiently
   // aligned object on the stack, store each element into it, then load
@@ -2806,6 +2851,9 @@
   case ISD::EXTRACT_SUBVECTOR:
     Results.push_back(ExpandExtractFromVectorThroughStack(SDValue(Node, 0)));
     break;
+  case ISD::INSERT_SUBVECTOR:
+    Results.push_back(ExpandInsertToVectorThroughStack(SDValue(Node, 0)));
+    break;
   case ISD::CONCAT_VECTORS: {
     Results.push_back(ExpandVectorBuildThroughStack(Node));
     break;
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
index 68d7621..661f810 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAG.cpp
@@ -3082,6 +3082,30 @@
   case ISD::VECTOR_SHUFFLE:
     llvm_unreachable("should use getVectorShuffle constructor!");
     break;
+  case ISD::INSERT_SUBVECTOR: {
+    SDValue Index = N3;
+    if (VT.isSimple() && N1.getValueType().isSimple()
+        && N2.getValueType().isSimple()) {
+      assert(VT.isVector() && N1.getValueType().isVector() &&
+             N2.getValueType().isVector() &&
+             "Insert subvector VTs must be a vectors");
+      assert(VT == N1.getValueType() &&
+             "Dest and insert subvector source types must match!");
+      assert(N2.getValueType().getSimpleVT() <= N1.getValueType().getSimpleVT() &&
+             "Insert subvector must be from smaller vector to larger vector!");
+      if (ConstantSDNode *CSD = dyn_cast<ConstantSDNode>(Index.getNode())) {
+        uint64_t Idx = CSD->getZExtValue();
+        assert((N2.getValueType().getVectorNumElements() + Idx
+                <= VT.getVectorNumElements())
+               && "Insert subvector overflow!");
+      }
+
+      // Trivial insertion.
+      if (VT.getSimpleVT() == N2.getValueType().getSimpleVT())
+        return N2;
+    }
+    break;
+  }
   case ISD::BITCAST:
     // Fold bit_convert nodes from a type to themselves.
     if (N1.getValueType() == VT)
@@ -5811,6 +5835,7 @@
   case ISD::INSERT_VECTOR_ELT:   return "insert_vector_elt";
   case ISD::EXTRACT_VECTOR_ELT:  return "extract_vector_elt";
   case ISD::CONCAT_VECTORS:      return "concat_vectors";
+  case ISD::INSERT_SUBVECTOR:    return "insert_subvector";
   case ISD::EXTRACT_SUBVECTOR:   return "extract_subvector";
   case ISD::SCALAR_TO_VECTOR:    return "scalar_to_vector";
   case ISD::VECTOR_SHUFFLE:      return "vector_shuffle";
diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index fb4495d..d519531 100644
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -568,8 +568,9 @@
     setOperationAction(ISD::LOAD, (MVT::SimpleValueType)VT, Expand);
     setOperationAction(ISD::VECTOR_SHUFFLE, (MVT::SimpleValueType)VT, Expand);
     setOperationAction(ISD::EXTRACT_VECTOR_ELT,(MVT::SimpleValueType)VT,Expand);
-    setOperationAction(ISD::EXTRACT_SUBVECTOR,(MVT::SimpleValueType)VT,Expand);
     setOperationAction(ISD::INSERT_VECTOR_ELT,(MVT::SimpleValueType)VT, Expand);
+    setOperationAction(ISD::EXTRACT_SUBVECTOR,(MVT::SimpleValueType)VT,Expand);
+    setOperationAction(ISD::INSERT_SUBVECTOR,(MVT::SimpleValueType)VT,Expand);
     setOperationAction(ISD::FABS, (MVT::SimpleValueType)VT, Expand);
     setOperationAction(ISD::FSIN, (MVT::SimpleValueType)VT, Expand);
     setOperationAction(ISD::FCOS, (MVT::SimpleValueType)VT, Expand);
@@ -5856,6 +5857,25 @@
   return SDValue();
 }
 
+// Lower a node with an INSERT_SUBVECTOR opcode.  This may result in a
+// simple superregister reference or explicit instructions to insert
+// the upper bits of a vector.
+SDValue
+X86TargetLowering::LowerINSERT_SUBVECTOR(SDValue Op, SelectionDAG &DAG) const {
+  if (Subtarget->hasAVX()) {
+    DebugLoc dl = Op.getNode()->getDebugLoc();
+    SDValue Vec = Op.getNode()->getOperand(0);
+    SDValue SubVec = Op.getNode()->getOperand(1);
+    SDValue Idx = Op.getNode()->getOperand(2);
+
+    if (Op.getNode()->getValueType(0).getSizeInBits() == 256
+        && SubVec.getNode()->getValueType(0).getSizeInBits() == 128) {
+      // TODO
+    }
+  }
+  return SDValue();
+}
+
 // ConstantPool, JumpTable, GlobalAddress, and ExternalSymbol are lowered as
 // their target countpart wrapped in the X86ISD::Wrapper node. Suppose N is
 // one of the above mentioned nodes. It has to be wrapped because otherwise
@@ -8705,6 +8725,7 @@
   case ISD::EXTRACT_VECTOR_ELT: return LowerEXTRACT_VECTOR_ELT(Op, DAG);
   case ISD::INSERT_VECTOR_ELT:  return LowerINSERT_VECTOR_ELT(Op, DAG);
   case ISD::EXTRACT_SUBVECTOR:  return LowerEXTRACT_SUBVECTOR(Op, DAG);
+  case ISD::INSERT_SUBVECTOR:   return LowerINSERT_SUBVECTOR(Op, DAG);
   case ISD::SCALAR_TO_VECTOR:   return LowerSCALAR_TO_VECTOR(Op, DAG);
   case ISD::ConstantPool:       return LowerConstantPool(Op, DAG);
   case ISD::GlobalAddress:      return LowerGlobalAddress(Op, DAG);
diff --git a/lib/Target/X86/X86ISelLowering.h b/lib/Target/X86/X86ISelLowering.h
index e81f041..8ede98a 100644
--- a/lib/Target/X86/X86ISelLowering.h
+++ b/lib/Target/X86/X86ISelLowering.h
@@ -742,6 +742,7 @@
     SDValue LowerINSERT_VECTOR_ELT_SSE4(SDValue Op, SelectionDAG &DAG) const;
     SDValue LowerSCALAR_TO_VECTOR(SDValue Op, SelectionDAG &DAG) const;
     SDValue LowerEXTRACT_SUBVECTOR(SDValue Op, SelectionDAG &DAG) const;
+    SDValue LowerINSERT_SUBVECTOR(SDValue Op, SelectionDAG &DAG) const;
     SDValue LowerConstantPool(SDValue Op, SelectionDAG &DAG) const;
     SDValue LowerBlockAddress(SDValue Op, SelectionDAG &DAG) const;
     SDValue LowerGlobalAddress(const GlobalValue *GV, DebugLoc dl,