diff --git a/llvm/include/llvm/CodeGen/LiveRangeEdit.h b/llvm/include/llvm/CodeGen/LiveRangeEdit.h
--- a/llvm/include/llvm/CodeGen/LiveRangeEdit.h
+++ b/llvm/include/llvm/CodeGen/LiveRangeEdit.h
@@ -134,10 +134,10 @@
       : Parent(parent), NewRegs(newRegs), MRI(MF.getRegInfo()), LIS(lis),
         VRM(vrm), TII(*MF.getSubtarget().getInstrInfo()), TheDelegate(delegate),
         FirstNew(newRegs.size()), DeadRemats(deadRemats) {
-    MRI.setDelegate(this);
+    MRI.setDelegate(this, DelegateReceiver::LRE);
   }
 
-  ~LiveRangeEdit() override { MRI.resetDelegate(this); }
+  ~LiveRangeEdit() override { MRI.resetDelegate(this, DelegateReceiver::LRE); }
 
   const LiveInterval &getParent() const {
     assert(Parent && "No parent LiveInterval");
diff --git a/llvm/include/llvm/CodeGen/MachineRegisterInfo.h b/llvm/include/llvm/CodeGen/MachineRegisterInfo.h
--- a/llvm/include/llvm/CodeGen/MachineRegisterInfo.h
+++ b/llvm/include/llvm/CodeGen/MachineRegisterInfo.h
@@ -44,6 +44,25 @@
 using RegClassOrRegBank =
     PointerUnion<const TargetRegisterClass *, const RegisterBank *>;
 
+/// Enum values for the intended delegate receivers.
+enum class DelegateReceiver : uint8_t {
+  LRE,     // For LiveRangeEdit
+  RESERVED // For target specific use
+};
+
+template <> struct DenseMapInfo<DelegateReceiver> {
+  static inline DelegateReceiver getEmptyKey() { return DelegateReceiver(-1); }
+  static inline DelegateReceiver getTombstoneKey() {
+    return DelegateReceiver(-2);
+  }
+  static unsigned getHashValue(DelegateReceiver val) {
+    return std::hash<unsigned>{}(unsigned(val));
+  }
+  static bool isEqual(DelegateReceiver LHS, DelegateReceiver RHS) {
+    return LHS == RHS;
+  }
+};
+
 /// MachineRegisterInfo - Keep track of information for virtual and physical
 /// registers, including vreg register classes, use/def chains for registers,
 /// etc.
@@ -56,11 +75,13 @@
     virtual ~Delegate() = default;
 
     virtual void MRI_NoteNewVirtualRegister(Register Reg) = 0;
+    virtual void MRI_NotecloneVirtualRegister(Register ClonedReg,
+                                              Register Reg) {}
   };
 
 private:
   MachineFunction *MF;
-  Delegate *TheDelegate = nullptr;
+  SmallDenseMap<DelegateReceiver, Delegate *, 1> TheDelegates;
 
   /// True if subregister liveness is tracked.
   const bool TracksSubRegLiveness;
@@ -152,21 +173,27 @@
     return MF->getSubtarget().getRegisterInfo();
   }
 
-  void resetDelegate(Delegate *delegate) {
+  Delegate *getDelegate(DelegateReceiver DR) {
+    if (TheDelegates.find(DR) == TheDelegates.end())
+      return nullptr;
+
+    return TheDelegates[DR];
+  }
+
+  void resetDelegate(Delegate *delegate, DelegateReceiver DR) {
     // Ensure another delegate does not take over unless the current
-    // delegate first unattaches itself. If we ever need to multicast
-    // notifications, we will need to change to using a list.
-    assert(TheDelegate == delegate &&
-           "Only the current delegate can perform reset!");
-    TheDelegate = nullptr;
+    // delegate first unattaches itself.
+    assert(getDelegate(DR) == delegate &&
+           "Only an existing delegate ca0n perform reset!");
+    TheDelegates.erase(DR);
   }
 
-  void setDelegate(Delegate *delegate) {
-    assert(delegate && !TheDelegate &&
-           "Attempted to set delegate to null, or to change it without "
+  void setDelegate(Delegate *delegate, DelegateReceiver DR) {
+    assert(delegate && !TheDelegates.count(DR) &&
+           "Attempted to add null delegate, or to change it without "
            "first resetting it!");
 
-    TheDelegate = delegate;
+    TheDelegates[DR] = delegate;
   }
 
   //===--------------------------------------------------------------------===//
diff --git a/llvm/lib/CodeGen/MachineRegisterInfo.cpp b/llvm/lib/CodeGen/MachineRegisterInfo.cpp
--- a/llvm/lib/CodeGen/MachineRegisterInfo.cpp
+++ b/llvm/lib/CodeGen/MachineRegisterInfo.cpp
@@ -48,6 +48,7 @@
   RegAllocHints.reserve(256);
   UsedPhysRegMask.resize(NumRegs);
   PhysRegUseDefLists.reset(new MachineOperand*[NumRegs]());
+  TheDelegates.clear();
 }
 
 /// setRegClass - Set the register class of the specified virtual register.
@@ -146,6 +147,9 @@
   VRegInfo.grow(Reg);
   RegAllocHints.grow(Reg);
   insertVRegByName(Name, Reg);
+  for (auto &TheDelegate : TheDelegates)
+    TheDelegate.second->MRI_NoteNewVirtualRegister(Reg);
+
   return Reg;
 }
 
@@ -162,8 +166,6 @@
   // New virtual register number.
   Register Reg = createIncompleteVirtualRegister(Name);
   VRegInfo[Reg].first = RegClass;
-  if (TheDelegate)
-    TheDelegate->MRI_NoteNewVirtualRegister(Reg);
   return Reg;
 }
 
@@ -172,8 +174,9 @@
   Register Reg = createIncompleteVirtualRegister(Name);
   VRegInfo[Reg].first = VRegInfo[VReg].first;
   setType(Reg, getType(VReg));
+  Delegate *TheDelegate = getDelegate(DelegateReceiver::RESERVED);
   if (TheDelegate)
-    TheDelegate->MRI_NoteNewVirtualRegister(Reg);
+    TheDelegate->MRI_NotecloneVirtualRegister(Reg, VReg);
   return Reg;
 }
 
@@ -189,8 +192,6 @@
   // FIXME: Should we use a dummy register class?
   VRegInfo[Reg].first = static_cast<RegisterBank *>(nullptr);
   setType(Reg, Ty);
-  if (TheDelegate)
-    TheDelegate->MRI_NoteNewVirtualRegister(Reg);
   return Reg;
 }