diff --git a/llvm/lib/CodeGen/SelectionDAG/LegalizeTypes.h b/llvm/lib/CodeGen/SelectionDAG/LegalizeTypes.h
--- a/llvm/lib/CodeGen/SelectionDAG/LegalizeTypes.h
+++ b/llvm/lib/CodeGen/SelectionDAG/LegalizeTypes.h
@@ -841,6 +841,7 @@
   SDValue SplitVecOp_TruncateHelper(SDNode *N);
 
   SDValue SplitVecOp_BITCAST(SDNode *N);
+  SDValue SplitVecOp_INSERT_SUBVECTOR(SDNode *N, unsigned OpNo);
   SDValue SplitVecOp_EXTRACT_SUBVECTOR(SDNode *N);
   SDValue SplitVecOp_EXTRACT_VECTOR_ELT(SDNode *N);
   SDValue SplitVecOp_ExtVecInRegOp(SDNode *N);
diff --git a/llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp b/llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp
--- a/llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp
@@ -2061,6 +2061,7 @@
   case ISD::SETCC:             Res = SplitVecOp_VSETCC(N); break;
   case ISD::BITCAST:           Res = SplitVecOp_BITCAST(N); break;
   case ISD::EXTRACT_SUBVECTOR: Res = SplitVecOp_EXTRACT_SUBVECTOR(N); break;
+  case ISD::INSERT_SUBVECTOR:  Res = SplitVecOp_INSERT_SUBVECTOR(N, OpNo); break;
   case ISD::EXTRACT_VECTOR_ELT:Res = SplitVecOp_EXTRACT_VECTOR_ELT(N); break;
   case ISD::CONCAT_VECTORS:    Res = SplitVecOp_CONCAT_VECTORS(N); break;
   case ISD::TRUNCATE:
@@ -2277,6 +2278,38 @@
                      JoinIntegers(Lo, Hi));
 }
 
+SDValue DAGTypeLegalizer::SplitVecOp_INSERT_SUBVECTOR(SDNode *N,
+                                                      unsigned OpNo) {
+  assert(OpNo == 1 && "Invalid OpNo; can only split SubVec.");
+  // We know that the result type is legal.
+  EVT ResVT = N->getValueType(0);
+
+  if (ResVT.isFixedLengthVector() &&
+      N->getOperand(0).getValueType().isFixedLengthVector() &&
+      N->getOperand(1).getValueType().isScalableVector())
+    report_fatal_error("Inserting a scalable vector into a fixed-length vector "
+                       "is not yet supported. ");
+
+  SDValue Vec = N->getOperand(0);
+  SDValue SubVec = N->getOperand(1);
+  SDValue Idx = N->getOperand(2);
+  SDLoc dl(N);
+
+  SDValue Lo, Hi;
+  GetSplitVector(SubVec, Lo, Hi);
+
+  uint64_t IdxVal = cast<ConstantSDNode>(Idx)->getZExtValue();
+  uint64_t LoElts = Lo.getValueType().getVectorMinNumElements();
+
+  SDValue FirstInsertion =
+      DAG.getNode(ISD::INSERT_SUBVECTOR, dl, ResVT, Vec, Lo, Idx);
+  SDValue SecondInsertion =
+      DAG.getNode(ISD::INSERT_SUBVECTOR, dl, ResVT, FirstInsertion, Hi,
+                  DAG.getVectorIdxConstant(IdxVal + LoElts, dl));
+
+  return SecondInsertion;
+}
+
 SDValue DAGTypeLegalizer::SplitVecOp_EXTRACT_SUBVECTOR(SDNode *N) {
   // We know that the extracted result type is legal.
   EVT SubVT = N->getValueType(0);