Index: llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
===================================================================
--- llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
+++ llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp
@@ -1,4 +1,4 @@
-//===- InstCombineCalls.cpp -----------------------------------------------===//
+//===- nstCombineCalls.cpp -----------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
@@ -1472,24 +1472,30 @@
 // start/end intrinsics in between). As this handles only the most trivial
 // cases, tracking the nesting level is not needed:
 //
-//   call @llvm.foo.start(i1 0) ; &I
 //   call @llvm.foo.start(i1 0)
-//   call @llvm.foo.end(i1 0) ; This one will not be skipped: it will be removed
+//   call @llvm.foo.start(i1 0) ; This one won't be skipped: it will be removed
 //   call @llvm.foo.end(i1 0)
-static bool removeTriviallyEmptyRange(IntrinsicInst &I, unsigned StartID,
-                                      unsigned EndID, InstCombiner &IC) {
-  assert(I.getIntrinsicID() == StartID &&
-         "Start intrinsic does not have expected ID");
-  BasicBlock::iterator BI(I), BE(I.getParent()->end());
-  for (++BI; BI != BE; ++BI) {
-    if (auto *E = dyn_cast<IntrinsicInst>(BI)) {
-      if (isa<DbgInfoIntrinsic>(E) || E->getIntrinsicID() == StartID)
+//   call @llvm.foo.end(i1 0) ; &I
+static bool removeTriviallyEmptyRange(
+    IntrinsicInst &EndI, InstCombiner &IC,
+    std::function<bool(const IntrinsicInst &)> IsStart) {
+  // We start from the end intrinsic and scan backwards, so that InstCombine
+  // has already processed (and potentially removed) all the instructions
+  // before the end intrinsic.
+  BasicBlock::reverse_iterator BI(EndI), BE(EndI.getParent()->rend());
+  for (; BI != BE; ++BI) {
+    if (auto *I = dyn_cast<IntrinsicInst>(&*BI)) {
+      if (isa<DbgInfoIntrinsic>(I) ||
+          I->getIntrinsicID() == EndI.getIntrinsicID())
+        continue;
+      if (IsStart(*I)) {
+        if (haveSameOperands(EndI, *I, EndI.getNumArgOperands())) {
+          IC.eraseInstFromFunction(*I);
+          IC.eraseInstFromFunction(EndI);
+          return true;
+        }
+        // Skip start intrinsics that don't pair with this end intrinsic.
         continue;
-      if (E->getIntrinsicID() == EndID &&
-          haveSameOperands(I, *E, E->getNumArgOperands())) {
-        IC.eraseInstFromFunction(*E);
-        IC.eraseInstFromFunction(I);
-        return true;
       }
     }
     break;
@@ -1747,13 +1753,11 @@
   llvm_unreachable("All SpecialCase enumerators should be handled in switch.");
 }
 
-Instruction *InstCombiner::visitVAStartInst(VAStartInst &I) {
-  removeTriviallyEmptyRange(I, Intrinsic::vastart, Intrinsic::vaend, *this);
-  return nullptr;
-}
-
-Instruction *InstCombiner::visitVACopyInst(VACopyInst &I) {
-  removeTriviallyEmptyRange(I, Intrinsic::vacopy, Intrinsic::vaend, *this);
+Instruction *InstCombiner::visitVAEndInst(VAEndInst &I) {
+  removeTriviallyEmptyRange(I, *this, [](const IntrinsicInst &I) {
+    return I.getIntrinsicID() == Intrinsic::vastart ||
+           I.getIntrinsicID() == Intrinsic::vacopy;
+  });
   return nullptr;
 }
 
@@ -4037,7 +4041,7 @@
       return eraseInstFromFunction(CI);
     break;
   }
-  case Intrinsic::lifetime_start:
+  case Intrinsic::lifetime_end:
     // Asan needs to poison memory to detect invalid access which is possible
     // even for empty lifetime range.
     if (II->getFunction()->hasFnAttribute(Attribute::SanitizeAddress) ||
@@ -4045,8 +4049,9 @@
         II->getFunction()->hasFnAttribute(Attribute::SanitizeHWAddress))
       break;
 
-    if (removeTriviallyEmptyRange(*II, Intrinsic::lifetime_start,
-                                  Intrinsic::lifetime_end, *this))
+    if (removeTriviallyEmptyRange(*II, *this, [](const IntrinsicInst &I) {
+          return I.getIntrinsicID() == Intrinsic::lifetime_start;
+        }))
       return nullptr;
     break;
   case Intrinsic::assume: {
Index: llvm/lib/Transforms/InstCombine/InstCombineInternal.h
===================================================================
--- llvm/lib/Transforms/InstCombine/InstCombineInternal.h
+++ llvm/lib/Transforms/InstCombine/InstCombineInternal.h
@@ -445,8 +445,7 @@
   Instruction *visitShuffleVectorInst(ShuffleVectorInst &SVI);
   Instruction *visitExtractValueInst(ExtractValueInst &EV);
   Instruction *visitLandingPadInst(LandingPadInst &LI);
-  Instruction *visitVAStartInst(VAStartInst &I);
-  Instruction *visitVACopyInst(VACopyInst &I);
+  Instruction *visitVAEndInst(VAEndInst &I);
   Instruction *visitFreeze(FreezeInst &I);
 
   /// Specify what to return for unhandled instructions.
Index: llvm/test/Transforms/InstCombine/lifetime.ll
===================================================================
--- llvm/test/Transforms/InstCombine/lifetime.ll
+++ llvm/test/Transforms/InstCombine/lifetime.ll
@@ -1,4 +1,4 @@
-; RUN: opt < %s -instcombine -S | FileCheck %s
+; RUN: opt < %s -instcombine -instcombine-infinite-loop-threshold=2 -S | FileCheck %s
 
 declare void @llvm.dbg.declare(metadata, metadata, metadata)
 declare void @llvm.lifetime.start.p0i8(i64, i8* nocapture)
Index: llvm/test/Transforms/InstCombine/vararg.ll
===================================================================
--- llvm/test/Transforms/InstCombine/vararg.ll
+++ llvm/test/Transforms/InstCombine/vararg.ll
@@ -1,4 +1,4 @@
-; RUN: opt < %s -instcombine -S | FileCheck %s
+; RUN: opt < %s -instcombine -instcombine-infinite-loop-threshold=2 -S | FileCheck %s
 
 %struct.__va_list = type { i8*, i8*, i8*, i32, i32 }