Index: llvm/trunk/lib/Transforms/Instrumentation/AddressSanitizer.cpp
===================================================================
--- llvm/trunk/lib/Transforms/Instrumentation/AddressSanitizer.cpp
+++ llvm/trunk/lib/Transforms/Instrumentation/AddressSanitizer.cpp
@@ -745,7 +745,8 @@
       return;
     // Find alloca instruction that corresponds to llvm.lifetime argument.
     AllocaInst *AI = findAllocaForValue(II.getArgOperand(1));
-    if (!AI) return;
+    if (!AI || !ASan.isInterestingAlloca(*AI))
+      return;
     bool DoPoison = (ID == Intrinsic::lifetime_end);
     AllocaPoisonCall APC = {&II, AI, SizeValue, DoPoison};
     AllocaPoisonCallVec.push_back(APC);
@@ -1984,13 +1985,21 @@
   assert(AllocaVec.size() > 0 || DynamicAllocaVec.size() > 0);
 
   // Insert poison calls for lifetime intrinsics for alloca.
-  bool HavePoisonedAllocas = false;
+  bool HavePoisonedStaticAllocas = false;
   for (const auto &APC : AllocaPoisonCallVec) {
     assert(APC.InsBefore);
     assert(APC.AI);
+    assert(ASan.isInterestingAlloca(*APC.AI));
+    bool IsDynamicAlloca = ASan.isDynamicAlloca(*APC.AI);
+    if (!ClInstrumentAllocas && IsDynamicAlloca)
+      continue;
+
     IRBuilder<> IRB(APC.InsBefore);
     poisonAlloca(APC.AI, APC.Size, IRB, APC.DoPoison);
-    HavePoisonedAllocas |= APC.DoPoison;
+    // Dynamic allocas will be unpoisoned unconditionally below in
+    // unpoisonDynamicAllocas.
+    // Flag that we need unpoison static allocas.
+    HavePoisonedStaticAllocas |= (APC.DoPoison && !IsDynamicAlloca);
   }
 
   if (ClInstrumentAllocas && DynamicAllocaVec.size() > 0) {
@@ -2137,7 +2146,7 @@
   poisonRedZones(L.ShadowBytes, IRB, ShadowBase, true);
 
   auto UnpoisonStack = [&](IRBuilder<> &IRB) {
-    if (HavePoisonedAllocas) {
+    if (HavePoisonedStaticAllocas) {
       // If we poisoned some allocas in llvm.lifetime analysis,
       // unpoison whole stack frame now.
       poisonAlloca(LocalStackBase, LocalStackSize, IRB, false);
Index: llvm/trunk/test/Instrumentation/AddressSanitizer/lifetime.ll
===================================================================
--- llvm/trunk/test/Instrumentation/AddressSanitizer/lifetime.ll
+++ llvm/trunk/test/Instrumentation/AddressSanitizer/lifetime.ll
@@ -1,5 +1,6 @@
 ; Test hanlding of llvm.lifetime intrinsics.
 ; RUN: opt < %s -asan -asan-module -asan-use-after-scope -asan-use-after-return=0 -S | FileCheck %s
+; RUN: opt < %s -asan -asan-module -asan-use-after-scope -asan-use-after-return=0 -asan-instrument-allocas=0 -S | FileCheck %s --check-prefix=CHECK-NO-DYNAMIC
 
 target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
 target triple = "x86_64-unknown-linux-gnu"
@@ -47,8 +48,10 @@
   call void @llvm.lifetime.start(i64 40, i8* %arr.ptr)
   store volatile i8 0, i8* %arr.ptr
   ; CHECK: call void @__asan_unpoison_stack_memory(i64 %{{[^ ]+}}, i64 40)
+  ; CHECK-NO-DYNAMIC-NOT: call void @__asan_unpoison_stack_memory(i64 %{{[^ ]+}}, i64 40)
   call void @llvm.lifetime.end(i64 40, i8* %arr.ptr)
   ; CHECK: call void @__asan_poison_stack_memory(i64 %{{[^ ]+}}, i64 40)
+  ; CHECK-NO-DYNAMIC-NOT: call void @__asan_poison_stack_memory(i64 %{{[^ ]+}}, i64 40)
 
   ; One more lifetime start/end for the same variable %i.
   call void @llvm.lifetime.start(i64 4, i8* %i.ptr)
@@ -87,3 +90,20 @@
   ; CHECK: ret void
   ret void
 }
+
+define void @zero_sized(i64 %a) #0 {
+; CHECK-LABEL: define void @zero_sized(i64 %a)
+
+entry:
+  %a.addr = alloca i64, align 8
+  %b = alloca [0 x i8], align 1
+  store i64 %a, i64* %a.addr, align 8
+  %0 = bitcast [0 x i8]* %b to i8*
+  call void @llvm.lifetime.start(i64 0, i8* %0) #2
+  ; CHECK-NOT: call void @__asan_unpoison_stack_memory
+  %1 = bitcast [0 x i8]* %b to i8*
+  call void @llvm.lifetime.end(i64 0, i8* %1) #2
+  ; CHECK-NOT: call void @__asan_poison_stack_memory
+
+  ret void
+}