Index: include/llvm/CodeGen/GlobalISel/LegalizerHelper.h
===================================================================
--- include/llvm/CodeGen/GlobalISel/LegalizerHelper.h
+++ include/llvm/CodeGen/GlobalISel/LegalizerHelper.h
@@ -57,8 +57,6 @@
   /// registers as \p MI.
   LegalizeResult legalizeInstrStep(MachineInstr &MI);
 
-  LegalizeResult legalizeInstr(MachineInstr &MI);
-
   /// Legalize an instruction by emiting a runtime library call instead.
   LegalizeResult libcall(MachineInstr &MI);
 
@@ -85,6 +83,10 @@
   LegalizeResult moreElementsVector(MachineInstr &MI, unsigned TypeIdx,
                                     LLT WideTy);
 
+  /// Expose MIRBuilder so clients can set their own RecordInsertInstruction
+  /// functions
+  MachineIRBuilder MIRBuilder;
+
 private:
 
   /// Helper function to split a wide generic register into bitwise blocks with
@@ -93,7 +95,6 @@
   void extractParts(unsigned Reg, LLT Ty, int NumParts,
                     SmallVectorImpl<unsigned> &Ops);
 
-  MachineIRBuilder MIRBuilder;
   MachineRegisterInfo &MRI;
   const LegalizerInfo &LI;
 };
Index: lib/CodeGen/GlobalISel/Legalizer.cpp
===================================================================
--- lib/CodeGen/GlobalISel/Legalizer.cpp
+++ lib/CodeGen/GlobalISel/Legalizer.cpp
@@ -171,21 +171,34 @@
       // and are assumed to be legal.
       if (!isPreISelGenericOpcode(MI->getOpcode()))
         continue;
-
-      auto Res = Helper.legalizeInstr(*MI);
-
-      // Error out if we couldn't legalize this instruction. We may want to fall
-      // back to DAG ISel instead in the future.
-      if (Res == LegalizerHelper::UnableToLegalize) {
-        reportGISelFailure(MF, TPC, MORE, "gisel-legalize",
-                           "unable to legalize instruction", *MI);
-        return false;
-      }
-
-      Changed |= Res == LegalizerHelper::Legalized;
+      SmallVector<MachineInstr *, 4> WorkList;
+      Helper.MIRBuilder.recordInsertions(
+          [&](MachineInstr *MI) { WorkList.push_back(MI); });
+      WorkList.push_back(&*MI);
+
+      LegalizerHelper::LegalizeResult Res;
+      unsigned Idx = 0;
+      do {
+        Res = Helper.legalizeInstrStep(*WorkList[Idx]);
+        // Error out if we couldn't legalize this instruction. We may want to
+        // fall
+        // back to DAG ISel instead in the future.
+        if (Res == LegalizerHelper::UnableToLegalize) {
+          Helper.MIRBuilder.stopRecordingInsertions();
+          if (Res == LegalizerHelper::UnableToLegalize) {
+            reportGISelFailure(MF, TPC, MORE, "gisel-legalize",
+                               "unable to legalize instruction",
+                               *WorkList[Idx]);
+            return false;
+          }
+        }
+        Changed |= Res == LegalizerHelper::Legalized;
+        ++Idx;
+      } while (Idx < WorkList.size());
+
+      Helper.MIRBuilder.stopRecordingInsertions();
     }
 
-
   MachineRegisterInfo &MRI = MF.getRegInfo();
   const TargetInstrInfo &TII = *MF.getSubtarget().getInstrInfo();
   for (auto &MBB : MF) {
Index: lib/CodeGen/GlobalISel/LegalizerHelper.cpp
===================================================================
--- lib/CodeGen/GlobalISel/LegalizerHelper.cpp
+++ lib/CodeGen/GlobalISel/LegalizerHelper.cpp
@@ -57,31 +57,6 @@
   }
 }
 
-LegalizerHelper::LegalizeResult
-LegalizerHelper::legalizeInstr(MachineInstr &MI) {
-  SmallVector<MachineInstr *, 4> WorkList;
-  MIRBuilder.recordInsertions(
-      [&](MachineInstr *MI) { WorkList.push_back(MI); });
-  WorkList.push_back(&MI);
-
-  bool Changed = false;
-  LegalizeResult Res;
-  unsigned Idx = 0;
-  do {
-    Res = legalizeInstrStep(*WorkList[Idx]);
-    if (Res == UnableToLegalize) {
-      MIRBuilder.stopRecordingInsertions();
-      return UnableToLegalize;
-    }
-    Changed |= Res == Legalized;
-    ++Idx;
-  } while (Idx < WorkList.size());
-
-  MIRBuilder.stopRecordingInsertions();
-
-  return Changed ? Legalized : AlreadyLegal;
-}
-
 void LegalizerHelper::extractParts(unsigned Reg, LLT Ty, int NumParts,
                                    SmallVectorImpl<unsigned> &VRegs) {
   for (int i = 0; i < NumParts; ++i)