diff --git a/llvm/include/llvm/CodeGen/GlobalISel/LegalizerHelper.h b/llvm/include/llvm/CodeGen/GlobalISel/LegalizerHelper.h
index f62ba12534d126..c6c57ac07f0e95 100644
--- a/llvm/include/llvm/CodeGen/GlobalISel/LegalizerHelper.h
+++ b/llvm/include/llvm/CodeGen/GlobalISel/LegalizerHelper.h
@@ -167,10 +167,6 @@ class LegalizerHelper {
   /// def by inserting a G_BITCAST from \p CastTy
   void bitcastDst(MachineInstr &MI, LLT CastTy, unsigned OpIdx);
 
-  /// Widen \p OrigReg to \p WideTy by merging to a wider type, padding with
-  /// G_IMPLICIT_DEF, and producing dead results.
-  Register widenWithUnmerge(LLT WideTy, Register OrigReg);
-
 private:
   LegalizeResult
   widenScalarMergeValues(MachineInstr &MI, unsigned TypeIdx, LLT WideTy);
diff --git a/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp b/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
index 5a945d1c797fcc..e8030df899a0fd 100644
--- a/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
@@ -1614,40 +1614,6 @@ LegalizerHelper::widenScalarMergeValues(MachineInstr &MI, unsigned TypeIdx,
   return Legalized;
 }
 
-Register LegalizerHelper::widenWithUnmerge(LLT WideTy, Register OrigReg) {
-  Register WideReg = MRI.createGenericVirtualRegister(WideTy);
-  LLT OrigTy = MRI.getType(OrigReg);
-  LLT LCMTy = getLCMType(WideTy, OrigTy);
-
-  const int NumMergeParts = LCMTy.getSizeInBits() / WideTy.getSizeInBits();
-  const int NumUnmergeParts = LCMTy.getSizeInBits() / OrigTy.getSizeInBits();
-
-  Register UnmergeSrc = WideReg;
-
-  // Create a merge to the LCM type, padding with undef
-  // %0:_(<3 x s32>) = G_FOO => <4 x s32>
-  // =>
-  // %1:_(<4 x s32>) = G_FOO
-  // %2:_(<4 x s32>) = G_IMPLICIT_DEF
-  // %3:_(<12 x s32>) = G_CONCAT_VECTORS %1, %2, %2
-  // %0:_(<3 x s32>), %4:_, %5:_, %6:_ = G_UNMERGE_VALUES %3
-  if (NumMergeParts > 1) {
-    Register Undef = MIRBuilder.buildUndef(WideTy).getReg(0);
-    SmallVector<Register, 8> MergeParts(NumMergeParts, Undef);
-    MergeParts[0] = WideReg;
-    UnmergeSrc = MIRBuilder.buildMerge(LCMTy, MergeParts).getReg(0);
-  }
-
-  // Unmerge to the original register and pad with dead defs.
-  SmallVector<Register, 8> UnmergeResults(NumUnmergeParts);
-  UnmergeResults[0] = OrigReg;
-  for (int I = 1; I != NumUnmergeParts; ++I)
-    UnmergeResults[I] = MRI.createGenericVirtualRegister(OrigTy);
-
-  MIRBuilder.buildUnmerge(UnmergeResults, UnmergeSrc);
-  return WideReg;
-}
-
 LegalizerHelper::LegalizeResult
 LegalizerHelper::widenScalarUnmergeValues(MachineInstr &MI, unsigned TypeIdx,
                                           LLT WideTy) {