diff --git a/llvm/lib/IR/Instructions.cpp b/llvm/lib/IR/Instructions.cpp
--- a/llvm/lib/IR/Instructions.cpp
+++ b/llvm/lib/IR/Instructions.cpp
@@ -45,6 +45,10 @@
 
 using namespace llvm;
 
+static cl::opt<bool> DisableI2pP2iOpt(
+    "disable-i2p-p2i-opt", cl::init(false),
+    cl::desc("Disables inttoptr/ptrtoint roundtrip optimization"));
+
 //===----------------------------------------------------------------------===//
 //                            AllocaInst Class
 //===----------------------------------------------------------------------===//
@@ -2768,7 +2772,7 @@
   // same reason.
   const unsigned numCastOps =
     Instruction::CastOpsEnd - Instruction::CastOpsBegin;
-  static const uint8_t CastResults[numCastOps][numCastOps] = {
+  static uint8_t CastResults[numCastOps][numCastOps] = {
     // T        F  F  U  S  F  F  P  I  B  A  -+
     // R  Z  S  P  P  I  I  T  P  2  N  T  S   |
     // U  E  E  2  2  2  2  R  E  I  T  C  C   +- secondOp
@@ -2789,6 +2793,9 @@
     {  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,13,12}, // AddrSpaceCast -+
   };
 
+  // Disable inttoptr/ptrtoint optimization if enabled.
+  if (DisableI2pP2iOpt)
+    CastResults[9][10] = 0;
   // TODO: This logic could be encoded into the table above and handled in the
   // switch below.
   // If either of the casts are a bitcast from scalar to vector, disallow the
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
--- a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -4539,6 +4539,21 @@
   auto *CastOp0 = dyn_cast<CastInst>(ICmp.getOperand(0));
   if (!CastOp0)
     return nullptr;
+
+  // icmp (inttoptr (ptrtoint p1)), p2 --> icmp p1, p2.
+  if (CastOp0->getOpcode() == Instruction::IntToPtr &&
+      (DL.getPointerTypeSizeInBits(CastOp0->getDestTy()) ==
+       DL.getTypeSizeInBits(CastOp0->getSrcTy()))) {
+    auto *I = dyn_cast<PtrToIntInst>(CastOp0->getOperand(0));
+    if (I && (DL.getPointerTypeSizeInBits(I->getSrcTy()) ==
+              DL.getTypeSizeInBits(I->getDestTy()))) {
+      Value *P = I->getOperand(0);
+      Type *Op0Ty = CastOp0->getDestTy();
+      Value *NewOp0 = Builder.CreateBitCast(P, Op0Ty);
+      return new ICmpInst(ICmp.getPredicate(), NewOp0, ICmp.getOperand(1));
+    }
+  }
+
   if (!isa<Constant>(ICmp.getOperand(1)) && !isa<CastInst>(ICmp.getOperand(1)))
     return nullptr;
 
diff --git a/llvm/test/Transforms/InstCombine/ptr-int-ptr-icmp.ll b/llvm/test/Transforms/InstCombine/ptr-int-ptr-icmp.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/Transforms/InstCombine/ptr-int-ptr-icmp.ll
@@ -0,0 +1,58 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -instcombine -S -disable-i2p-p2i-opt < %s | FileCheck %s
+
+target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+; icmp (inttoptr (ptrtoint p1)), p2 --> icmp p1, p2.
+
+define i1 @func(i8* %X, i8* %Y) {
+; CHECK-LABEL: @func(
+; CHECK-NEXT:    [[CMP:%.*]] = icmp eq i8* [[X:%.*]], [[Y:%.*]]
+; CHECK-NEXT:    ret i1 [[CMP]]
+;
+  %i = ptrtoint i8* %X to i64
+  %p = inttoptr i64 %i to i8*
+  %cmp = icmp eq i8* %p, %Y
+  ret i1 %cmp
+}
+
+define i1 @func2(i16* %X, i8* %Y) {
+; CHECK-LABEL: @func2(
+; CHECK-NEXT:    [[TMP1:%.*]] = bitcast i16* [[X:%.*]] to i8*
+; CHECK-NEXT:    [[CMP:%.*]] = icmp eq i8* [[TMP1]], [[Y:%.*]]
+; CHECK-NEXT:    ret i1 [[CMP]]
+;
+  %i = ptrtoint i16* %X to i64
+  %p = inttoptr i64 %i to i8*
+  %cmp = icmp eq i8* %p, %Y
+  ret i1 %cmp
+}
+
+define i1 @func3(i16* %X, i8* %Y) {
+; CHECK-LABEL: @func3(
+; CHECK-NEXT:    [[TMP1:%.*]] = bitcast i16* [[X:%.*]] to i8*
+; CHECK-NEXT:    [[CMP:%.*]] = icmp eq i8* [[TMP1]], [[Y:%.*]]
+; CHECK-NEXT:    ret i1 [[CMP]]
+;
+  %i = ptrtoint i16* %X to i64
+  %p = inttoptr i64 %i to i8*
+  %cmp = icmp eq i8* %Y, %p
+  ret i1 %cmp
+}
+
+; Negative test - Wrong Integer type.
+
+define i1 @func4(i16* %X, i8* %Y) {
+; CHECK-LABEL: @func4(
+; CHECK-NEXT:    [[TMP1:%.*]] = ptrtoint i16* [[X:%.*]] to i64
+; CHECK-NEXT:    [[TMP2:%.*]] = and i64 [[TMP1]], 4294967295
+; CHECK-NEXT:    [[P:%.*]] = inttoptr i64 [[TMP2]] to i8*
+; CHECK-NEXT:    [[CMP:%.*]] = icmp eq i8* [[P]], [[Y:%.*]]
+; CHECK-NEXT:    ret i1 [[CMP]]
+;
+  %i = ptrtoint i16* %X to i32
+  %p = inttoptr i32 %i to i8*
+  %cmp = icmp eq i8* %Y, %p
+  ret i1 %cmp
+}