diff --git a/llvm/include/llvm/IR/BasicBlock.h b/llvm/include/llvm/IR/BasicBlock.h
index 179305e9260f9..86d026126316d 100644
--- a/llvm/include/llvm/IR/BasicBlock.h
+++ b/llvm/include/llvm/IR/BasicBlock.h
@@ -14,6 +14,7 @@
 #define LLVM_IR_BASICBLOCK_H
 
 #include "llvm-c/Types.h"
+#include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/Twine.h"
 #include "llvm/ADT/ilist.h"
 #include "llvm/ADT/ilist_node.h"
@@ -21,7 +22,6 @@
 #include "llvm/ADT/iterator_range.h"
 #include "llvm/IR/DebugProgramInstruction.h"
 #include "llvm/IR/Instruction.h"
-#include "llvm/IR/DebugProgramInstruction.h"
 #include "llvm/IR/SymbolTableListTraits.h"
 #include "llvm/IR/Value.h"
 #include <cassert>
@@ -774,6 +774,32 @@ BasicBlock::iterator skipDebugIntrinsics(BasicBlock::iterator It);
 inline void BasicBlock::validateInstrOrdering() const {}
 #endif
 
+// Specialize DenseMapInfo for iterators, so that ththey can be installed into
+// maps and sets. The iterator is made up of its node pointer, and the
+// debug-info "head" bit.
+template <> struct DenseMapInfo<BasicBlock::iterator> {
+  static inline BasicBlock::iterator getEmptyKey() {
+    return BasicBlock::iterator(nullptr);
+  }
+
+  static inline BasicBlock::iterator getTombstoneKey() {
+    BasicBlock::iterator It(nullptr);
+    It.setHeadBit(true);
+    return It;
+  }
+
+  static unsigned getHashValue(const BasicBlock::iterator &It) {
+    return DenseMapInfo<void *>::getHashValue(
+               reinterpret_cast<void *>(It.getNodePtr())) ^
+           It.getHeadBit();
+  }
+
+  static bool isEqual(const BasicBlock::iterator &LHS,
+                      const BasicBlock::iterator &RHS) {
+    return LHS == RHS && LHS.getHeadBit() == RHS.getHeadBit();
+  }
+};
+
 } // end namespace llvm
 
 #endif // LLVM_IR_BASICBLOCK_H
diff --git a/llvm/include/llvm/Transforms/Scalar/ConstantHoisting.h b/llvm/include/llvm/Transforms/Scalar/ConstantHoisting.h
index a4d1653fdf4bc..48f8421c1813c 100644
--- a/llvm/include/llvm/Transforms/Scalar/ConstantHoisting.h
+++ b/llvm/include/llvm/Transforms/Scalar/ConstantHoisting.h
@@ -172,11 +172,12 @@ class ConstantHoistingPass : public PassInfoMixin<ConstantHoistingPass> {
 
   void collectMatInsertPts(
       const consthoist::RebasedConstantListType &RebasedConstants,
-      SmallVectorImpl<Instruction *> &MatInsertPts) const;
-  Instruction *findMatInsertPt(Instruction *Inst, unsigned Idx = ~0U) const;
-  SetVector<Instruction *>
-  findConstantInsertionPoint(const consthoist::ConstantInfo &ConstInfo,
-                             const ArrayRef<Instruction *> MatInsertPts) const;
+      SmallVectorImpl<BasicBlock::iterator> &MatInsertPts) const;
+  BasicBlock::iterator findMatInsertPt(Instruction *Inst,
+                                       unsigned Idx = ~0U) const;
+  SetVector<BasicBlock::iterator> findConstantInsertionPoint(
+      const consthoist::ConstantInfo &ConstInfo,
+      const ArrayRef<BasicBlock::iterator> MatInsertPts) const;
   void collectConstantCandidates(ConstCandMapType &ConstCandMap,
                                  Instruction *Inst, unsigned Idx,
                                  ConstantInt *ConstInt);
@@ -203,9 +204,9 @@ class ConstantHoistingPass : public PassInfoMixin<ConstantHoistingPass> {
   struct UserAdjustment {
     Constant *Offset;
     Type *Ty;
-    Instruction *MatInsertPt;
+    BasicBlock::iterator MatInsertPt;
     const consthoist::ConstantUser User;
-    UserAdjustment(Constant *O, Type *T, Instruction *I,
+    UserAdjustment(Constant *O, Type *T, BasicBlock::iterator I,
                    consthoist::ConstantUser U)
         : Offset(O), Ty(T), MatInsertPt(I), User(U) {}
   };
diff --git a/llvm/lib/Transforms/Scalar/ConstantHoisting.cpp b/llvm/lib/Transforms/Scalar/ConstantHoisting.cpp
index 49f8761a13923..4f9d9c84fe930 100644
--- a/llvm/lib/Transforms/Scalar/ConstantHoisting.cpp
+++ b/llvm/lib/Transforms/Scalar/ConstantHoisting.cpp
@@ -162,27 +162,27 @@ bool ConstantHoistingLegacyPass::runOnFunction(Function &Fn) {
 
 void ConstantHoistingPass::collectMatInsertPts(
     const RebasedConstantListType &RebasedConstants,
-    SmallVectorImpl<Instruction *> &MatInsertPts) const {
+    SmallVectorImpl<BasicBlock::iterator> &MatInsertPts) const {
   for (const RebasedConstantInfo &RCI : RebasedConstants)
     for (const ConstantUser &U : RCI.Uses)
       MatInsertPts.emplace_back(findMatInsertPt(U.Inst, U.OpndIdx));
 }
 
 /// Find the constant materialization insertion point.
-Instruction *ConstantHoistingPass::findMatInsertPt(Instruction *Inst,
-                                                   unsigned Idx) const {
+BasicBlock::iterator ConstantHoistingPass::findMatInsertPt(Instruction *Inst,
+                                                           unsigned Idx) const {
   // If the operand is a cast instruction, then we have to materialize the
   // constant before the cast instruction.
   if (Idx != ~0U) {
     Value *Opnd = Inst->getOperand(Idx);
     if (auto CastInst = dyn_cast<Instruction>(Opnd))
       if (CastInst->isCast())
-        return CastInst;
+        return CastInst->getIterator();
   }
 
   // The simple and common case. This also includes constant expressions.
   if (!isa<PHINode>(Inst) && !Inst->isEHPad())
-    return Inst;
+    return Inst->getIterator();
 
   // We can't insert directly before a phi node or an eh pad. Insert before
   // the terminator of the incoming or dominating block.
@@ -191,7 +191,7 @@ Instruction *ConstantHoistingPass::findMatInsertPt(Instruction *Inst,
   if (Idx != ~0U && isa<PHINode>(Inst)) {
     InsertionBlock = cast<PHINode>(Inst)->getIncomingBlock(Idx);
     if (!InsertionBlock->isEHPad()) {
-      return InsertionBlock->getTerminator();
+      return InsertionBlock->getTerminator()->getIterator();
     }
   } else {
     InsertionBlock = Inst->getParent();
@@ -206,7 +206,7 @@ Instruction *ConstantHoistingPass::findMatInsertPt(Instruction *Inst,
     IDom = IDom->getIDom();
   }
 
-  return IDom->getBlock()->getTerminator();
+  return IDom->getBlock()->getTerminator()->getIterator();
 }
 
 /// Given \p BBs as input, find another set of BBs which collectively
@@ -314,26 +314,27 @@ static void findBestInsertionSet(DominatorTree &DT, BlockFrequencyInfo &BFI,
 }
 
 /// Find an insertion point that dominates all uses.
-SetVector<Instruction *> ConstantHoistingPass::findConstantInsertionPoint(
+SetVector<BasicBlock::iterator>
+ConstantHoistingPass::findConstantInsertionPoint(
     const ConstantInfo &ConstInfo,
-    const ArrayRef<Instruction *> MatInsertPts) const {
+    const ArrayRef<BasicBlock::iterator> MatInsertPts) const {
   assert(!ConstInfo.RebasedConstants.empty() && "Invalid constant info entry.");
   // Collect all basic blocks.
   SetVector<BasicBlock *> BBs;
-  SetVector<Instruction *> InsertPts;
+  SetVector<BasicBlock::iterator> InsertPts;
 
-  for (Instruction *MatInsertPt : MatInsertPts)
+  for (BasicBlock::iterator MatInsertPt : MatInsertPts)
     BBs.insert(MatInsertPt->getParent());
 
   if (BBs.count(Entry)) {
-    InsertPts.insert(&Entry->front());
+    InsertPts.insert(Entry->begin());
     return InsertPts;
   }
 
   if (BFI) {
     findBestInsertionSet(*DT, *BFI, Entry, BBs);
     for (BasicBlock *BB : BBs)
-      InsertPts.insert(&*BB->getFirstInsertionPt());
+      InsertPts.insert(BB->getFirstInsertionPt());
     return InsertPts;
   }
 
@@ -343,7 +344,7 @@ SetVector<Instruction *> ConstantHoistingPass::findConstantInsertionPoint(
     BB2 = BBs.pop_back_val();
     BB = DT->findNearestCommonDominator(BB1, BB2);
     if (BB == Entry) {
-      InsertPts.insert(&Entry->front());
+      InsertPts.insert(Entry->begin());
       return InsertPts;
     }
     BBs.insert(BB);
@@ -761,11 +762,13 @@ void ConstantHoistingPass::emitBaseConstants(Instruction *Base,
       Mat = GetElementPtrInst::Create(Type::getInt8Ty(*Ctx), Base, Adj->Offset,
                                       "mat_gep", Adj->MatInsertPt);
       // Hide it behind a bitcast.
-      Mat = new BitCastInst(Mat, Adj->Ty, "mat_bitcast", Adj->MatInsertPt);
+      Mat = new BitCastInst(Mat, Adj->Ty, "mat_bitcast",
+                            Adj->MatInsertPt->getIterator());
     } else
       // Constant being rebased is a ConstantInt.
-      Mat = BinaryOperator::Create(Instruction::Add, Base, Adj->Offset,
-                                   "const_mat", Adj->MatInsertPt);
+      Mat =
+          BinaryOperator::Create(Instruction::Add, Base, Adj->Offset,
+                                 "const_mat", Adj->MatInsertPt->getIterator());
 
     LLVM_DEBUG(dbgs() << "Materialize constant (" << *Base->getOperand(0)
                       << " + " << *Adj->Offset << ") in BB "
@@ -816,7 +819,8 @@ void ConstantHoistingPass::emitBaseConstants(Instruction *Base,
 
     // Aside from constant GEPs, only constant cast expressions are collected.
     assert(ConstExpr->isCast() && "ConstExpr should be a cast");
-    Instruction *ConstExprInst = ConstExpr->getAsInstruction(Adj->MatInsertPt);
+    Instruction *ConstExprInst = ConstExpr->getAsInstruction();
+    ConstExprInst->insertBefore(Adj->MatInsertPt);
     ConstExprInst->setOperand(0, Mat);
 
     // Use the same debug location as the instruction we are about to update.
@@ -842,9 +846,9 @@ bool ConstantHoistingPass::emitBaseConstants(GlobalVariable *BaseGV) {
   SmallVectorImpl<consthoist::ConstantInfo> &ConstInfoVec =
       BaseGV ? ConstGEPInfoMap[BaseGV] : ConstIntInfoVec;
   for (const consthoist::ConstantInfo &ConstInfo : ConstInfoVec) {
-    SmallVector<Instruction *, 4> MatInsertPts;
+    SmallVector<BasicBlock::iterator, 4> MatInsertPts;
     collectMatInsertPts(ConstInfo.RebasedConstants, MatInsertPts);
-    SetVector<Instruction *> IPSet =
+    SetVector<BasicBlock::iterator> IPSet =
         findConstantInsertionPoint(ConstInfo, MatInsertPts);
     // We can have an empty set if the function contains unreachable blocks.
     if (IPSet.empty())
@@ -853,7 +857,7 @@ bool ConstantHoistingPass::emitBaseConstants(GlobalVariable *BaseGV) {
     unsigned UsesNum = 0;
     unsigned ReBasesNum = 0;
     unsigned NotRebasedNum = 0;
-    for (Instruction *IP : IPSet) {
+    for (const BasicBlock::iterator &IP : IPSet) {
       // First, collect constants depending on this IP of the base.
       UsesNum = 0;
       SmallVector<UserAdjustment, 4> ToBeRebased;
@@ -861,7 +865,7 @@ bool ConstantHoistingPass::emitBaseConstants(GlobalVariable *BaseGV) {
       for (auto const &RCI : ConstInfo.RebasedConstants) {
         UsesNum += RCI.Uses.size();
         for (auto const &U : RCI.Uses) {
-          Instruction *MatInsertPt = MatInsertPts[MatCtr++];
+          const BasicBlock::iterator &MatInsertPt = MatInsertPts[MatCtr++];
           BasicBlock *OrigMatInsertBB = MatInsertPt->getParent();
           // If Base constant is to be inserted in multiple places,
           // generate rebase for U using the Base dominating U.