Index: lib/Transforms/Scalar/SROA.cpp
===================================================================
--- lib/Transforms/Scalar/SROA.cpp
+++ lib/Transforms/Scalar/SROA.cpp
@@ -1735,9 +1735,13 @@
     if (!S.isSplittable())
       return false; // Skip any unsplittable intrinsics.
   } else if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(U->getUser())) {
+    // lifetime.start and lifetime.end are promotable, but we avoid
+    // promoting them in some cases if asan is enabled.
     if (II->getIntrinsicID() != Intrinsic::lifetime_start &&
         II->getIntrinsicID() != Intrinsic::lifetime_end)
       return false;
+    if (II->getFunction()->hasFnAttribute(Attribute::SanitizeAddress))
+      return false;
   } else if (U->get()->getType()->getPointerElementType()->isStructTy()) {
     // Disable vector promotion when there are loads or stores of an FCA.
     return false;
@@ -1947,9 +1951,13 @@
     if (!S.isSplittable())
       return false; // Skip any unsplittable intrinsics.
   } else if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(U->getUser())) {
+    // lifetime.start and lifetime.end are promotable, but we avoid
+    // promoting them in some cases if asan is enabled.
     if (II->getIntrinsicID() != Intrinsic::lifetime_start &&
         II->getIntrinsicID() != Intrinsic::lifetime_end)
       return false;
+    if (II->getFunction()->hasFnAttribute(Attribute::SanitizeAddress))
+      return false;
   } else {
     return false;
   }
@@ -2875,6 +2883,23 @@
     // Record this instruction for deletion.
     Pass.DeadInsts.insert(&II);
 
+    // Lifetime intrinsics are only promotable if they cover the whole alloca.
+    // Therefore, we drop lifetime intrinsics which don't cover the whole
+    // alloca.
+    //
+    // As an exception to this rule, don't drop the intrinsics if asan is
+    // enabled, to enable more precise lifetime tracking.
+    //
+    // (In theory, intrinsics which partially cover an alloca could be
+    // promoted, but PromoteMemToReg doesn't handle that case.)
+    // FIXME: Check whether the alloca is promotable before dropping the
+    // lifetime intrinsics?
+    bool IsWholeAlloca = NewBeginOffset == NewAllocaBeginOffset &&
+                         NewEndOffset == NewAllocaEndOffset;
+    if (!II.getFunction()->hasFnAttribute(Attribute::SanitizeAddress) &&
+        !IsWholeAlloca)
+      return true;
+
     ConstantInt *Size =
         ConstantInt::get(cast<IntegerType>(II.getArgOperand(0)->getType()),
                          NewEndOffset - NewBeginOffset);
@@ -2888,11 +2913,6 @@
     (void)New;
     DEBUG(dbgs() << "          to: " << *New << "\n");
 
-    // Lifetime intrinsics are only promotable if they cover the whole alloca.
-    // (In theory, intrinsics which partially cover an alloca could be
-    // promoted, but PromoteMemToReg doesn't handle that case.)
-    bool IsWholeAlloca = NewBeginOffset == NewAllocaBeginOffset &&
-                         NewEndOffset == NewAllocaEndOffset;
     return IsWholeAlloca;
   }
 
Index: test/Transforms/SROA/basictest.ll
===================================================================
--- test/Transforms/SROA/basictest.ll
+++ test/Transforms/SROA/basictest.ll
@@ -1672,6 +1672,20 @@
 
 define void @PR27999() unnamed_addr {
 ; CHECK-LABEL: @PR27999(
+; CHECK: entry-block:
+; CHECK-NEXT: ret void
+entry-block:
+  %0 = alloca [2 x i64], align 8
+  %1 = bitcast [2 x i64]* %0 to i8*
+  call void @llvm.lifetime.start(i64 16, i8* %1)
+  %2 = getelementptr inbounds [2 x i64], [2 x i64]* %0, i32 0, i32 1
+  %3 = bitcast i64* %2 to i8*
+  call void @llvm.lifetime.end(i64 8, i8* %3)
+  ret void
+}
+
+define void @PR27999_asan() sanitize_address {
+; CHECK-LABEL: @PR27999_asan(
 ; CHECK: alloca [2 x i64], align 8
 ; CHECK: call void @llvm.lifetime.start(i64 16,
 ; CHECK: call void @llvm.lifetime.end(i64 8,
@@ -1684,3 +1698,27 @@
   call void @llvm.lifetime.end(i64 8, i8* %3)
   ret void
 }
+
+define void @PR29139() {
+; CHECK-LABEL: @PR29139(
+; CHECK: bb1:
+; CHECK-NEXT: ret void
+bb1:
+  %e.7.sroa.6.i = alloca i32, align 1
+  %e.7.sroa.6.0.load81.i = load i32, i32* %e.7.sroa.6.i, align 1
+  %0 = bitcast i32* %e.7.sroa.6.i to i8*
+  call void @llvm.lifetime.end(i64 2, i8* %0)
+  ret void
+}
+
+define void @PR29139_asan() sanitize_address {
+; CHECK-LABEL: @PR29139_asan(
+; CHECK: alloca i32
+; CHECK: call void @llvm.lifetime.end(i64 2
+bb1:
+  %e.7.sroa.6.i = alloca i32, align 1
+  %e.7.sroa.6.0.load81.i = load i32, i32* %e.7.sroa.6.i, align 1
+  %0 = bitcast i32* %e.7.sroa.6.i to i8*
+  call void @llvm.lifetime.end(i64 2, i8* %0)
+  ret void
+}