Index: lib/Transforms/InstCombine/InstCombineCalls.cpp
===================================================================
--- lib/Transforms/InstCombine/InstCombineCalls.cpp
+++ lib/Transforms/InstCombine/InstCombineCalls.cpp
@@ -1392,6 +1392,24 @@
       return EraseInstFromFunction(CI);
     break;
   }
+  case Intrinsic::lifetime_start: {
+    // Remove trivially empty lifetime_start/end ranges, i.e. a start
+    // immediately followed by an end (ignoring debuginfo in between).
+    BasicBlock::iterator BI = II, BE = II->getParent()->end();
+    for (++BI; BI != BE; ++BI) {
+      if (isa<DbgInfoIntrinsic>(BI))
+        continue;
+      if (IntrinsicInst *LTE = dyn_cast<IntrinsicInst>(BI))
+        if (LTE->getIntrinsicID() == Intrinsic::lifetime_end &&
+            II->getOperand(0) == LTE->getOperand(0) &&
+            II->getOperand(1) == LTE->getOperand(1)) {
+          EraseInstFromFunction(*LTE);
+          return EraseInstFromFunction(*II);
+        }
+      break;
+    }
+    break;
+  }
   case Intrinsic::assume: {
     // Canonicalize assume(a && b) -> assume(a); assume(b);
     // Note: New assumption intrinsics created here are registered by
Index: test/Transforms/InstCombine/lifetime.ll
===================================================================
--- /dev/null
+++ test/Transforms/InstCombine/lifetime.ll
@@ -0,0 +1,43 @@
+; RUN: opt < %s -instcombine -S | FileCheck %s
+; RUN: opt < %s -instcombine -S | grep lifetime | count 6
+
+declare void @llvm.lifetime.start(i64, i8* nocapture)
+declare void @llvm.lifetime.end(i64, i8* nocapture)
+declare void @bar(i8* nocapture, i8* nocapture)
+
+define void @foo(i1 %flag) {
+entry:
+; CHECK-LABEL: @foo(
+; CHECK: %[[T:[^ ]+]] = getelementptr inbounds [1 x i8], [1 x i8]* %t
+; CHECK: %[[B:[^ ]+]] = getelementptr inbounds [1 x i8], [1 x i8]* %b
+; CHECK: call void @llvm.lifetime.start(i64 1, i8* %[[T]])
+; CHECK-NEXT: call void @llvm.lifetime.start(i64 1, i8* %[[B]])
+; CHECK-NEXT: call void @bar(i8* %[[B]], i8* %[[T]])
+; CHECK-NEXT: call void @llvm.lifetime.end(i64 1, i8* %[[B]])
+; CHECK-NEXT: call void @llvm.lifetime.end(i64 1, i8* %[[T]])
+  %t = alloca [1 x i8], align 1
+  %b = alloca [1 x i8], align 1
+  %0 = getelementptr inbounds [1 x i8], [1 x i8]* %t, i64 0, i64 0
+  %1 = getelementptr inbounds [1 x i8], [1 x i8]* %b, i64 0, i64 0
+  br i1 %flag, label %if, label %else
+
+if:
+  call void @llvm.lifetime.start(i64 1, i8* %0)
+  call void @llvm.lifetime.start(i64 1, i8* %1)
+  call void @llvm.lifetime.end(i64 1, i8* %1)
+  call void @llvm.lifetime.end(i64 1, i8* %0)
+  br label %fin
+
+else:
+  call void @llvm.lifetime.start(i64 1, i8* %0)
+  call void @llvm.lifetime.start(i64 1, i8* %1)
+  call void @bar(i8* %1, i8* %0)
+  call void @llvm.lifetime.end(i64 1, i8* %1)
+  call void @llvm.lifetime.end(i64 1, i8* %0)
+  br  label %fin
+
+fin:
+  ret void
+}
+
+