Index: include/llvm/CodeGen/GlobalISel/MachineIRBuilder.h
===================================================================
--- include/llvm/CodeGen/GlobalISel/MachineIRBuilder.h
+++ include/llvm/CodeGen/GlobalISel/MachineIRBuilder.h
@@ -731,6 +731,9 @@
   MachineInstrBuilder buildUnmerge(ArrayRef<LLT> Res, const SrcOp &Op);
   MachineInstrBuilder buildUnmerge(ArrayRef<unsigned> Res, const SrcOp &Op);
 
+  /// Build and insert an unmerge of \p Res sized pieces to cover \p Op
+  MachineInstrBuilder buildUnmerge(LLT Res, const SrcOp &Op);
+
   /// Build and insert \p Res = G_BUILD_VECTOR \p Op0, ...
   ///
   /// G_BUILD_VECTOR creates a vector value from multiple scalar registers.
Index: lib/CodeGen/GlobalISel/MachineIRBuilder.cpp
===================================================================
--- lib/CodeGen/GlobalISel/MachineIRBuilder.cpp
+++ lib/CodeGen/GlobalISel/MachineIRBuilder.cpp
@@ -547,6 +547,15 @@
   return buildInstr(TargetOpcode::G_UNMERGE_VALUES, TmpVec, Op);
 }
 
+MachineInstrBuilder MachineIRBuilder::buildUnmerge(LLT Res,
+                                                   const SrcOp &Op) {
+  unsigned NumReg = Op.getLLTTy(*getMRI()).getSizeInBits() / Res.getSizeInBits();
+  SmallVector<unsigned, 8> TmpVec;
+  for (unsigned I = 0; I != NumReg; ++I)
+    TmpVec.push_back(getMRI()->createGenericVirtualRegister(Res));
+  return buildUnmerge(TmpVec, Op);
+}
+
 MachineInstrBuilder MachineIRBuilder::buildUnmerge(ArrayRef<unsigned> Res,
                                                    const SrcOp &Op) {
   // Unfortunately to convert from ArrayRef<unsigned> to ArrayRef<DstOp>,