Index: llvm/include/llvm/ADT/PointerIntPair.h
===================================================================
--- llvm/include/llvm/ADT/PointerIntPair.h
+++ llvm/include/llvm/ADT/PointerIntPair.h
@@ -19,10 +19,37 @@
 #include "llvm/Support/type_traits.h"
 #include <cassert>
 #include <cstdint>
+#include <cstring>
 #include <limits>
 
 namespace llvm {
 
+namespace detail {
+template <typename Ptr> struct PunnedPointer {
+  explicit constexpr PunnedPointer(intptr_t i = 0) { *this = i; }
+
+  intptr_t asInt() const {
+    intptr_t R = 0;
+    std::memcpy(&R, &Data, sizeof(R));
+    return R;
+  }
+
+  constexpr operator intptr_t() const { return asInt(); }
+
+  constexpr PunnedPointer &operator=(intptr_t V) {
+    std::memcpy(&Data, &V, sizeof(Data));
+    return *this;
+  }
+
+  Ptr *getPointerAddress() { return reinterpret_cast<Ptr *>(Data); }
+  const Ptr *getPointerAddress() const {
+    return const_cast<PunnedPointer *>(this)->getPointerAddress();
+  }
+
+  alignas(Ptr) char Data[sizeof(Ptr)];
+};
+} // namespace detail
+
 template <typename T, typename Enable> struct DenseMapInfo;
 template <typename PointerT, unsigned IntBits, typename PtrTraits>
 struct PointerIntPairInfo;
@@ -46,7 +73,7 @@
 class PointerIntPair {
   // Used by MSVC visualizer and generally helpful for debugging/visualizing.
   using InfoTy = Info;
-  intptr_t Value = 0;
+  detail::PunnedPointer<PointerTy> Value;
 
 public:
   constexpr PointerIntPair() = default;
@@ -86,10 +113,12 @@
     assert(Value == reinterpret_cast<intptr_t>(getPointer()) &&
            "Can only return the address if IntBits is cleared and "
            "PtrTraits doesn't change the pointer");
-    return reinterpret_cast<PointerTy *>(&Value);
+    return Value.getPointerAddress();
   }
 
-  void *getOpaqueValue() const { return reinterpret_cast<void *>(Value); }
+  void *getOpaqueValue() const {
+    return reinterpret_cast<void *>(Value.asInt());
+  }
 
   void setFromOpaqueValue(void *Val) & {
     Value = reinterpret_cast<intptr_t>(Val);
Index: llvm/unittests/ADT/PointerIntPairTest.cpp
===================================================================
--- llvm/unittests/ADT/PointerIntPairTest.cpp
+++ llvm/unittests/ADT/PointerIntPairTest.cpp
@@ -106,4 +106,22 @@
       "trivially copyable");
 }
 
+TEST(PointerIntPairTest, TypePunning) {
+  int i = 0;
+  int *intPtr = &i;
+
+  int **intPtrBegin = &intPtr;
+  int **intPtrEnd = intPtrBegin + 1;
+
+  PointerIntPair<int *, 1> pair;
+  int **pairAddr = pair.getAddrOfPointer();
+
+  while (intPtrBegin != intPtrEnd) {
+    *pairAddr = *intPtrBegin;
+    ++pairAddr;
+    ++intPtrBegin;
+  }
+  EXPECT_EQ(pair.getPointer(), intPtr);
+}
+
 } // end anonymous namespace