Index: include/llvm/CodeGen/MachineMemOperand.h
===================================================================
--- include/llvm/CodeGen/MachineMemOperand.h
+++ include/llvm/CodeGen/MachineMemOperand.h
@@ -286,6 +286,10 @@
   void setValue(const PseudoSourceValue *NewSV) { PtrInfo.V = NewSV; }
   void setOffset(int64_t NewOffset) { PtrInfo.Offset = NewOffset; }
 
+  /// Create new MachineMemOperand that represents a \p Size byte subset located
+  /// at \p Offset.
+  MachineMemOperand *copyWithSizeAndOffset(MachineFunction &MF, unsigned Size,
+                                           unsigned Offset) const;
   /// Profile - Gather unique data for the object.
   ///
   void Profile(FoldingSetNodeID &ID) const;
Index: lib/CodeGen/GlobalISel/LegalizerHelper.cpp
===================================================================
--- lib/CodeGen/GlobalISel/LegalizerHelper.cpp
+++ lib/CodeGen/GlobalISel/LegalizerHelper.cpp
@@ -493,16 +493,13 @@
     for (int i = 0; i < NumParts; ++i) {
       unsigned DstReg = MRI.createGenericVirtualRegister(NarrowTy);
       unsigned SrcReg = 0;
-      unsigned Adjustment = i * NarrowSize / 8;
-      unsigned Alignment = MinAlign(MMO.getAlignment(), Adjustment);
+      unsigned Offset = i * NarrowSize / 8;
 
-      MachineMemOperand *SplitMMO = MIRBuilder.getMF().getMachineMemOperand(
-          MMO.getPointerInfo().getWithOffset(Adjustment), MMO.getFlags(),
-          NarrowSize / 8, Alignment, MMO.getAAInfo(), MMO.getRanges(),
-          MMO.getSyncScopeID(), MMO.getOrdering(), MMO.getFailureOrdering());
+      MachineMemOperand *SplitMMO = MMO.copyWithSizeAndOffset(
+          MIRBuilder.getMF(), NarrowSize / 8, Offset);
 
       MIRBuilder.materializeGEP(SrcReg, MI.getOperand(1).getReg(), OffsetTy,
-                                Adjustment);
+                                Offset);
 
       MIRBuilder.buildLoad(DstReg, SrcReg, *SplitMMO);
 
@@ -565,16 +562,13 @@
 
     for (int i = 0; i < NumParts; ++i) {
       unsigned DstReg = 0;
-      unsigned Adjustment = i * NarrowSize / 8;
-      unsigned Alignment = MinAlign(MMO.getAlignment(), Adjustment);
+      unsigned Offset = i * NarrowSize / 8;
 
-      MachineMemOperand *SplitMMO = MIRBuilder.getMF().getMachineMemOperand(
-          MMO.getPointerInfo().getWithOffset(Adjustment), MMO.getFlags(),
-          NarrowSize / 8, Alignment, MMO.getAAInfo(), MMO.getRanges(),
-          MMO.getSyncScopeID(), MMO.getOrdering(), MMO.getFailureOrdering());
+      MachineMemOperand *SplitMMO =
+          MMO.copyWithSizeAndOffset(MIRBuilder.getMF(), NarrowSize / 8, Offset);
 
       MIRBuilder.materializeGEP(DstReg, MI.getOperand(1).getReg(), OffsetTy,
-                                Adjustment);
+                                Offset);
 
       MIRBuilder.buildStore(SrcRegs[i], DstReg, *SplitMMO);
     }
Index: lib/CodeGen/MachineOperand.cpp
===================================================================
--- lib/CodeGen/MachineOperand.cpp
+++ lib/CodeGen/MachineOperand.cpp
@@ -1004,6 +1004,14 @@
   assert(getFailureOrdering() == FailureOrdering && "Value truncated");
 }
 
+MachineMemOperand *
+MachineMemOperand::copyWithSizeAndOffset(MachineFunction &MF, unsigned Size,
+                                         unsigned Offset) const {
+  return MF.getMachineMemOperand(getPointerInfo().getWithOffset(Offset),
+                                 getFlags(), Size,
+                                 MinAlign(getAlignment(), Offset));
+}
+
 /// Profile - Gather unique data for the object.
 ///
 void MachineMemOperand::Profile(FoldingSetNodeID &ID) const {