diff --git a/llvm/include/llvm/CodeGen/GlobalISel/CallLowering.h b/llvm/include/llvm/CodeGen/GlobalISel/CallLowering.h
index 3bee9734d8a15..0e6392084a503 100644
--- a/llvm/include/llvm/CodeGen/GlobalISel/CallLowering.h
+++ b/llvm/include/llvm/CodeGen/GlobalISel/CallLowering.h
@@ -355,9 +355,13 @@ class CallLowering {
   /// Break \p OrigArgInfo into one or more pieces the calling convention can
   /// process, returned in \p SplitArgs. For example, this should break structs
   /// down into individual fields.
+  ///
+  /// If \p Offsets is non-null, it points to a vector to be filled in
+  /// with the in-memory offsets of each of the individual values.
   void splitToValueTypes(const ArgInfo &OrigArgInfo,
                          SmallVectorImpl<ArgInfo> &SplitArgs,
-                         const DataLayout &DL, CallingConv::ID CallConv) const;
+                         const DataLayout &DL, CallingConv::ID CallConv,
+                         SmallVectorImpl<uint64_t> *Offsets = nullptr) const;
 
   /// Generate instructions for unpacking \p SrcReg into the \p DstRegs
   /// corresponding to the aggregate type \p PackedTy.
diff --git a/llvm/lib/CodeGen/GlobalISel/CallLowering.cpp b/llvm/lib/CodeGen/GlobalISel/CallLowering.cpp
index 282414170a8df..a1658969ea22e 100644
--- a/llvm/lib/CodeGen/GlobalISel/CallLowering.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/CallLowering.cpp
@@ -207,12 +207,12 @@ CallLowering::setArgFlags<CallBase>(CallLowering::ArgInfo &Arg, unsigned OpIdx,
 void CallLowering::splitToValueTypes(const ArgInfo &OrigArg,
                                      SmallVectorImpl<ArgInfo> &SplitArgs,
                                      const DataLayout &DL,
-                                     CallingConv::ID CallConv) const {
+                                     CallingConv::ID CallConv,
+                                     SmallVectorImpl<uint64_t> *Offsets) const {
   LLVMContext &Ctx = OrigArg.Ty->getContext();
 
   SmallVector<EVT, 4> SplitVTs;
-  SmallVector<uint64_t, 4> Offsets;
-  ComputeValueVTs(*TLI, DL, OrigArg.Ty, SplitVTs, &Offsets, 0);
+  ComputeValueVTs(*TLI, DL, OrigArg.Ty, SplitVTs, Offsets, 0);
 
   if (SplitVTs.size() == 0)
     return;