Index: clang/lib/Driver/SanitizerArgs.cpp
===================================================================
--- clang/lib/Driver/SanitizerArgs.cpp
+++ clang/lib/Driver/SanitizerArgs.cpp
@@ -491,7 +491,7 @@
     MsanUseAfterDtor =
         Args.hasFlag(options::OPT_fsanitize_memory_use_after_dtor,
                      options::OPT_fno_sanitize_memory_use_after_dtor,
-                     false);
+                     true);
     NeedPIE |= !(TC.getTriple().isOSLinux() &&
                  TC.getTriple().getArch() == llvm::Triple::x86_64);
   }
Index: clang/test/CodeGenCXX/sanitize-no-dtor-callback.cpp
===================================================================
--- clang/test/CodeGenCXX/sanitize-no-dtor-callback.cpp
+++ clang/test/CodeGenCXX/sanitize-no-dtor-callback.cpp
@@ -1,8 +1,9 @@
-// Test without the flag -fsanitize-memory-use-after-dtor, to ensure that
+// Test with the flag -fno-sanitize-memory-use-after-dtor, to ensure that
 // instrumentation is not erroneously inserted
-// RUN: %clang_cc1 -fsanitize=memory -triple=x86_64-pc-linux -emit-llvm -o - %s | FileCheck %s
+// RUN: %clang_cc1 -fsanitize=memory -fno-sanitize-memory-use-after-dtor -triple=x86_64-pc-linux -emit-llvm -o - %s | FileCheck %s
 
 struct Simple {
+  int x;
   ~Simple() {}
 };
 Simple s;
@@ -10,6 +11,7 @@
 // CHECK-NOT: call void @__sanitizer_dtor_callback
 
 struct Inlined {
+  int y;
   inline ~Inlined() {}
 };
 Inlined i;
Index: clang/test/Driver/fsanitize.c
===================================================================
--- clang/test/Driver/fsanitize.c
+++ clang/test/Driver/fsanitize.c
@@ -174,11 +174,11 @@
 
 // RUN: %clang -target x86_64-linux-gnu -fsanitize=memory -fsanitize-memory-use-after-dtor %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-USE-AFTER-DTOR
 // RUN: %clang -target x86_64-linux-gnu -fsanitize=memory -fno-sanitize-memory-use-after-dtor -fsanitize-memory-use-after-dtor %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-USE-AFTER-DTOR
+// RUN: %clang -target x86_64-linux-gnu -fsanitize=memory %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-USE-AFTER-DTOR
 // CHECK-USE-AFTER-DTOR: -cc1{{.*}}-fsanitize-memory-use-after-dtor
 
 // RUN: %clang -target x86_64-linux-gnu -fsanitize=memory -fno-sanitize-memory-use-after-dtor %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-USE-AFTER-DTOR-OFF
 // RUN: %clang -target x86_64-linux-gnu -fsanitize=memory -fsanitize-memory-use-after-dtor -fno-sanitize-memory-use-after-dtor %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-USE-AFTER-DTOR-OFF
-// RUN: %clang -target x86_64-linux-gnu -fsanitize=memory %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-USE-AFTER-DTOR-OFF
 // CHECK-USE-AFTER-DTOR-OFF-NOT: -cc1{{.*}}memory-use-after-dtor
 
 // RUN: %clang -target x86_64-linux-gnu -fsanitize=address -fsanitize-address-field-padding=0 %s -### 2>&1 | FileCheck %s --check-prefix=CHECK-ASAN-FIELD-PADDING-0
Index: compiler-rt/test/msan/dtor-member.cc
===================================================================
--- compiler-rt/test/msan/dtor-member.cc
+++ compiler-rt/test/msan/dtor-member.cc
@@ -7,7 +7,7 @@
 // RUN: %clangxx_msan %s -O2 -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && MSAN_OPTIONS=poison_in_dtor=1  %run %t >%t.out 2>&1
 // RUN: FileCheck %s < %t.out
 
-// RUN: %clangxx_msan %s -fsanitize=memory -o %t && MSAN_OPTIONS=poison_in_dtor=1  %run %t >%t.out 2>&1
+// RUN: %clangxx_msan %s -fsanitize=memory -fno-sanitize-memory-use-after-dtor -o %t && MSAN_OPTIONS=poison_in_dtor=1  %run %t >%t.out 2>&1
 // RUN: FileCheck %s --check-prefix=CHECK-NO-FLAG < %t.out
 
 // RUN: %clangxx_msan -fsanitize=memory -fsanitize-memory-use-after-dtor %s -o %t && MSAN_OPTIONS=poison_in_dtor=0 %run %t >%t.out 2>&1
Index: compiler-rt/test/msan/use-after-dtor.cc
===================================================================
--- compiler-rt/test/msan/use-after-dtor.cc
+++ compiler-rt/test/msan/use-after-dtor.cc
@@ -1,14 +1,17 @@
 // RUN: %clangxx_msan %s -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && MSAN_OPTIONS=poison_in_dtor=1 not %run %t >%t.out 2>&1
-// RUN: FileCheck %s < %t.out
+// RUN: FileCheck %s --check-prefix=CHECK-UAD < %t.out
 
 // RUN: %clangxx_msan %s -O1 -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && MSAN_OPTIONS=poison_in_dtor=1 not %run %t >%t.out 2>&1
-// RUN: FileCheck %s < %t.out
+// RUN: FileCheck %s --check-prefix=CHECK-UAD < %t.out
 
 // RUN: %clangxx_msan %s -O2 -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && MSAN_OPTIONS=poison_in_dtor=1 not %run %t >%t.out 2>&1
-// RUN: FileCheck %s < %t.out
+// RUN: FileCheck %s --check-prefix=CHECK-UAD < %t.out
 
 // RUN: %clangxx_msan %s -O1 -fsanitize=memory -fsanitize-memory-use-after-dtor -fsanitize-memory-track-origins -o %t && MSAN_OPTIONS=poison_in_dtor=1 not %run %t >%t.out 2>&1
-// RUN: FileCheck %s --check-prefix=CHECK-ORIGINS < %t.out
+// RUN: FileCheck %s --check-prefixes=CHECK-UAD,CHECK-ORIGINS < %t.out
+
+// RUN: %clangxx_msan %s -fno-sanitize-memory-use-after-dtor -o %t && MSAN_OPTIONS=poison_in_dtor=1 not %run %t >%t.out 2>&1
+// RUN: FileCheck %s --check-prefix=CHECK-UAD-OFF < %t.out
 
 #include <sanitizer/msan_interface.h>
 #include <assert.h>
@@ -32,14 +35,17 @@
   Simple *s = new(&buf) Simple();
   s->~Simple();
 
+  fprintf(stderr, "\n");  // Need output to parse for CHECK-UAD-OFF case
   return s->x_;
 
-  // CHECK: WARNING: MemorySanitizer: use-of-uninitialized-value
-  // CHECK: {{#0 0x.* in main.*use-after-dtor.cc:}}[[@LINE-3]]
+  // CHECK-UAD: WARNING: MemorySanitizer: use-of-uninitialized-value
+  // CHECK-UAD: {{#0 0x.* in main.*use-after-dtor.cc:}}[[@LINE-3]]
+  // CHECK-UAD-OFF-NOT: WARNING: MemorySanitizer: use-of-uninitialized-value
 
   // CHECK-ORIGINS: Memory was marked as uninitialized
   // CHECK-ORIGINS: {{#0 0x.* in __sanitizer_dtor_callback}}
   // CHECK-ORIGINS: {{#1 0x.* in Simple::~Simple}}
 
-  // CHECK: SUMMARY: MemorySanitizer: use-of-uninitialized-value {{.*main}}
+  // CHECK-UAD: SUMMARY: MemorySanitizer: use-of-uninitialized-value {{.*main}}
+  // CHECK-UAD-OFF-NOT: SUMMARY: MemorySanitizer: use-of-uninitialized-value
 }