diff --git a/compiler-rt/lib/msan/msan_flags.inc b/compiler-rt/lib/msan/msan_flags.inc
--- a/compiler-rt/lib/msan/msan_flags.inc
+++ b/compiler-rt/lib/msan/msan_flags.inc
@@ -24,7 +24,7 @@
 MSAN_FLAG(bool, poison_stack_with_zeroes, false, "")
 MSAN_FLAG(bool, poison_in_malloc, true, "")
 MSAN_FLAG(bool, poison_in_free, true, "")
-MSAN_FLAG(bool, poison_in_dtor, false, "")
+MSAN_FLAG(bool, poison_in_dtor, true, "")
 MSAN_FLAG(bool, report_umrs, true, "")
 MSAN_FLAG(bool, wrap_signals, true, "")
 MSAN_FLAG(bool, print_stats, false, "")
diff --git a/compiler-rt/test/fuzzer/msan.test b/compiler-rt/test/fuzzer/msan.test
--- a/compiler-rt/test/fuzzer/msan.test
+++ b/compiler-rt/test/fuzzer/msan.test
@@ -17,7 +17,7 @@
 
 
 RUN: %msan_compiler %S/UseAfterDtor.cpp -o %t
-RUN: MSAN_OPTIONS=poison_in_dtor=1 not %run %t -seed=1 -runs=10000000 2>&1 | FileCheck %s --check-prefix=REPORT
+RUN: not %run %t -seed=1 -runs=10000000 2>&1 | FileCheck %s --check-prefix=REPORT
 
 RUN: %msan_compiler %S/UninitializedStrlen.cpp -o %t
 RUN: not %run %t -seed=1 -runs=10000000 2>&1 | FileCheck %s --check-prefix=REPORT
diff --git a/compiler-rt/test/msan/dtor-base-access.cpp b/compiler-rt/test/msan/dtor-base-access.cpp
--- a/compiler-rt/test/msan/dtor-base-access.cpp
+++ b/compiler-rt/test/msan/dtor-base-access.cpp
@@ -1,8 +1,8 @@
-// RUN: %clangxx_msan %s -O0 -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && MSAN_OPTIONS=poison_in_dtor=1 %run %t >%t.out 2>&1
+// RUN: %clangxx_msan %s -O0 -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && %run %t >%t.out 2>&1
 
-// RUN: %clangxx_msan %s -O1 -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && MSAN_OPTIONS=poison_in_dtor=1 %run %t >%t.out 2>&1
+// RUN: %clangxx_msan %s -O1 -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && %run %t >%t.out 2>&1
 
-// 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: %clangxx_msan %s -O2 -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && %run %t >%t.out 2>&1
 
 #include <sanitizer/msan_interface.h>
 #include <assert.h>
diff --git a/compiler-rt/test/msan/dtor-bit-fields.cpp b/compiler-rt/test/msan/dtor-bit-fields.cpp
--- a/compiler-rt/test/msan/dtor-bit-fields.cpp
+++ b/compiler-rt/test/msan/dtor-bit-fields.cpp
@@ -1,8 +1,8 @@
-// RUN: %clangxx_msan %s -O0 -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && MSAN_OPTIONS=poison_in_dtor=1 %run %t
+// RUN: %clangxx_msan %s -O0 -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && %run %t
 
-// RUN: %clangxx_msan %s -O1 -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && MSAN_OPTIONS=poison_in_dtor=1 %run %t
+// RUN: %clangxx_msan %s -O1 -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && %run %t
 
-// RUN: %clangxx_msan %s -O2 -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && MSAN_OPTIONS=poison_in_dtor=1 %run %t
+// RUN: %clangxx_msan %s -O2 -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && %run %t
 
 #include <sanitizer/msan_interface.h>
 #include <assert.h>
diff --git a/compiler-rt/test/msan/dtor-derived-class.cpp b/compiler-rt/test/msan/dtor-derived-class.cpp
--- a/compiler-rt/test/msan/dtor-derived-class.cpp
+++ b/compiler-rt/test/msan/dtor-derived-class.cpp
@@ -1,6 +1,6 @@
-// RUN: %clangxx_msan %s -O0 -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && MSAN_OPTIONS=poison_in_dtor=1 %run %t >%t.out 2>&1
-// RUN: %clangxx_msan %s -O1 -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && MSAN_OPTIONS=poison_in_dtor=1 %run %t >%t.out 2>&1
-// 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: %clangxx_msan %s -O0 -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && %run %t >%t.out 2>&1
+// RUN: %clangxx_msan %s -O1 -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && %run %t >%t.out 2>&1
+// RUN: %clangxx_msan %s -O2 -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && %run %t >%t.out 2>&1
 
 #include <sanitizer/msan_interface.h>
 #include <assert.h>
diff --git a/compiler-rt/test/msan/dtor-member.cpp b/compiler-rt/test/msan/dtor-member.cpp
--- a/compiler-rt/test/msan/dtor-member.cpp
+++ b/compiler-rt/test/msan/dtor-member.cpp
@@ -1,13 +1,13 @@
-// RUN: %clangxx_msan %s -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && MSAN_OPTIONS=poison_in_dtor=1 %run %t >%t.out 2>&1
+// RUN: %clangxx_msan %s -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && %run %t >%t.out 2>&1
 // RUN: FileCheck %s < %t.out
 
-// RUN: %clangxx_msan %s -O1 -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && MSAN_OPTIONS=poison_in_dtor=1 %run %t >%t.out 2>&1
+// RUN: %clangxx_msan %s -O1 -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && %run %t >%t.out 2>&1
 // RUN: FileCheck %s < %t.out
 
-// 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: %clangxx_msan %s -O2 -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t &&  %run %t >%t.out 2>&1
 // RUN: FileCheck %s < %t.out
 
-// 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: %clangxx_msan %s -fsanitize=memory -fno-sanitize-memory-use-after-dtor -o %t &&  %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
diff --git a/compiler-rt/test/msan/dtor-multiple-inheritance-nontrivial-class-members.cpp b/compiler-rt/test/msan/dtor-multiple-inheritance-nontrivial-class-members.cpp
--- a/compiler-rt/test/msan/dtor-multiple-inheritance-nontrivial-class-members.cpp
+++ b/compiler-rt/test/msan/dtor-multiple-inheritance-nontrivial-class-members.cpp
@@ -1,8 +1,8 @@
-// RUN: %clangxx_msan %s -O0 -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && MSAN_OPTIONS=poison_in_dtor=1 %run %t >%t.out 2>&1
+// RUN: %clangxx_msan %s -O0 -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && %run %t >%t.out 2>&1
 
-// RUN: %clangxx_msan %s -O1 -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && MSAN_OPTIONS=poison_in_dtor=1 %run %t >%t.out 2>&1
+// RUN: %clangxx_msan %s -O1 -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && %run %t >%t.out 2>&1
 
-// 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: %clangxx_msan %s -O2 -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && %run %t >%t.out 2>&1
 
 #include <sanitizer/msan_interface.h>
 #include <assert.h>
diff --git a/compiler-rt/test/msan/dtor-multiple-inheritance.cpp b/compiler-rt/test/msan/dtor-multiple-inheritance.cpp
--- a/compiler-rt/test/msan/dtor-multiple-inheritance.cpp
+++ b/compiler-rt/test/msan/dtor-multiple-inheritance.cpp
@@ -5,11 +5,11 @@
 //  \ /
 //   Derived
 
-// RUN: %clangxx_msan %s -O0 -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && MSAN_OPTIONS=poison_in_dtor=1 %run %t >%t.out 2>&1
+// RUN: %clangxx_msan %s -O0 -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && %run %t >%t.out 2>&1
 
-// RUN: %clangxx_msan %s -O1 -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && MSAN_OPTIONS=poison_in_dtor=1 %run %t >%t.out 2>&1
+// RUN: %clangxx_msan %s -O1 -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && %run %t >%t.out 2>&1
 
-// 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: %clangxx_msan %s -O2 -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && %run %t >%t.out 2>&1
 
 #include <sanitizer/msan_interface.h>
 #include <assert.h>
diff --git a/compiler-rt/test/msan/dtor-trivial-class-members.cpp b/compiler-rt/test/msan/dtor-trivial-class-members.cpp
--- a/compiler-rt/test/msan/dtor-trivial-class-members.cpp
+++ b/compiler-rt/test/msan/dtor-trivial-class-members.cpp
@@ -1,8 +1,8 @@
-// RUN: %clangxx_msan %s -O0 -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && MSAN_OPTIONS=poison_in_dtor=1 %run %t >%t.out 2>&1
+// RUN: %clangxx_msan %s -O0 -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && %run %t >%t.out 2>&1
 
-// RUN: %clangxx_msan %s -O1 -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && MSAN_OPTIONS=poison_in_dtor=1 %run %t >%t.out 2>&1
+// RUN: %clangxx_msan %s -O1 -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && %run %t >%t.out 2>&1
 
-// 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: %clangxx_msan %s -O2 -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && %run %t >%t.out 2>&1
 
 #include <sanitizer/msan_interface.h>
 #include <assert.h>
diff --git a/compiler-rt/test/msan/dtor-trivial.cpp b/compiler-rt/test/msan/dtor-trivial.cpp
--- a/compiler-rt/test/msan/dtor-trivial.cpp
+++ b/compiler-rt/test/msan/dtor-trivial.cpp
@@ -1,8 +1,8 @@
-// RUN: %clangxx_msan %s -O0 -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && MSAN_OPTIONS=poison_in_dtor=1 %run %t >%t.out 2>&1
+// RUN: %clangxx_msan %s -O0 -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && %run %t >%t.out 2>&1
 
-// RUN: %clangxx_msan %s -O1 -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && MSAN_OPTIONS=poison_in_dtor=1 %run %t >%t.out 2>&1
+// RUN: %clangxx_msan %s -O1 -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && %run %t >%t.out 2>&1
 
-// 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: %clangxx_msan %s -O2 -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && %run %t >%t.out 2>&1
 
 // TODO Success pending on resolution of
 // https://github.com/google/sanitizers/issues/596
diff --git a/compiler-rt/test/msan/dtor-vtable-multiple-inheritance.cpp b/compiler-rt/test/msan/dtor-vtable-multiple-inheritance.cpp
--- a/compiler-rt/test/msan/dtor-vtable-multiple-inheritance.cpp
+++ b/compiler-rt/test/msan/dtor-vtable-multiple-inheritance.cpp
@@ -1,14 +1,14 @@
-// RUN: %clangxx_msan %s -O0 -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && MSAN_OPTIONS=poison_in_dtor=1 %run %t
+// RUN: %clangxx_msan %s -O0 -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && %run %t
 
-// RUN: %clangxx_msan %s -O1 -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && MSAN_OPTIONS=poison_in_dtor=1 %run %t
+// RUN: %clangxx_msan %s -O1 -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && %run %t
 
-// RUN: %clangxx_msan %s -O2 -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && MSAN_OPTIONS=poison_in_dtor=1 %run %t
+// RUN: %clangxx_msan %s -O2 -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && %run %t
 
-// RUN: %clangxx_msan %s -DCVPTR=1 -O2 -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && MSAN_OPTIONS=poison_in_dtor=1 not %run %t
+// RUN: %clangxx_msan %s -DCVPTR=1 -O2 -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && not %run %t
 
-// RUN: %clangxx_msan %s -DEAVPTR=1 -O2 -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && MSAN_OPTIONS=poison_in_dtor=1 not %run %t
+// RUN: %clangxx_msan %s -DEAVPTR=1 -O2 -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && not %run %t
 
-// RUN: %clangxx_msan %s -DEDVPTR=1 -O2 -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && MSAN_OPTIONS=poison_in_dtor=1 not %run %t
+// RUN: %clangxx_msan %s -DEDVPTR=1 -O2 -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && not %run %t
 
 // Expected to quit due to invalid access when invoking
 // function using vtable.
diff --git a/compiler-rt/test/msan/dtor-vtable.cpp b/compiler-rt/test/msan/dtor-vtable.cpp
--- a/compiler-rt/test/msan/dtor-vtable.cpp
+++ b/compiler-rt/test/msan/dtor-vtable.cpp
@@ -1,16 +1,16 @@
-// RUN: %clangxx_msan %s -O0 -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && MSAN_OPTIONS=poison_in_dtor=1 %run %t
+// RUN: %clangxx_msan %s -O0 -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && %run %t
 
-// RUN: %clangxx_msan %s -O1 -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && MSAN_OPTIONS=poison_in_dtor=1 %run %t
+// RUN: %clangxx_msan %s -O1 -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && %run %t
 
-// RUN: %clangxx_msan %s -O2 -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && MSAN_OPTIONS=poison_in_dtor=1 %run %t
+// RUN: %clangxx_msan %s -O2 -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && %run %t
 
-// RUN: %clangxx_msan %s -DVPTRA=1 -O2 -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && MSAN_OPTIONS=poison_in_dtor=1 not %run %t
+// RUN: %clangxx_msan %s -DVPTRA=1 -O2 -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && not %run %t
 
-// RUN: %clangxx_msan %s -DVPTRCA=1 -O2 -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && MSAN_OPTIONS=poison_in_dtor=1 not %run %t
+// RUN: %clangxx_msan %s -DVPTRCA=1 -O2 -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && not %run %t
 
-// RUN: %clangxx_msan %s -DVPTRCB=1 -O2 -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && MSAN_OPTIONS=poison_in_dtor=1 not %run %t
+// RUN: %clangxx_msan %s -DVPTRCB=1 -O2 -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && not %run %t
 
-// RUN: %clangxx_msan %s -DVPTRC=1 -O2 -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && MSAN_OPTIONS=poison_in_dtor=1 not %run %t
+// RUN: %clangxx_msan %s -DVPTRC=1 -O2 -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && not %run %t
 
 // Expected to quit due to invalid access when invoking
 // function using vtable.
diff --git a/compiler-rt/test/msan/poison_in_signal.cpp b/compiler-rt/test/msan/poison_in_signal.cpp
--- a/compiler-rt/test/msan/poison_in_signal.cpp
+++ b/compiler-rt/test/msan/poison_in_signal.cpp
@@ -2,7 +2,7 @@
 
 // RUN: %clangxx_msan -std=c++11 -O2 %s -o %t && %run %t
 // RUN: %clangxx_msan -fsanitize-memory-track-origins=2 -std=c++11 -O2 %s -o %t && %run %t
-// RUN: %clangxx_msan -fsanitize-memory-track-origins=2 -fsanitize-memory-use-after-dtor -std=c++11 -O2 %s -o %t && MSAN_OPTIONS=poison_in_dtor=1 %run %t
+// RUN: %clangxx_msan -fsanitize-memory-track-origins=2 -fsanitize-memory-use-after-dtor -std=c++11 -O2 %s -o %t && %run %t
 
 #include <assert.h>
 #include <atomic>
diff --git a/compiler-rt/test/msan/use-after-dtor.cpp b/compiler-rt/test/msan/use-after-dtor.cpp
--- a/compiler-rt/test/msan/use-after-dtor.cpp
+++ b/compiler-rt/test/msan/use-after-dtor.cpp
@@ -1,16 +1,16 @@
-// 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: %clangxx_msan %s -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && not %run %t >%t.out 2>&1
 // 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: %clangxx_msan %s -O1 -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && not %run %t >%t.out 2>&1
 // 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: %clangxx_msan %s -O2 -fsanitize=memory -fsanitize-memory-use-after-dtor -o %t && not %run %t >%t.out 2>&1
 // 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: %clangxx_msan %s -O1 -fsanitize=memory -fsanitize-memory-use-after-dtor -fsanitize-memory-track-origins -o %t && not %run %t >%t.out 2>&1
 // 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: %clangxx_msan %s -fno-sanitize-memory-use-after-dtor -o %t && not %run %t > %t.out 2>&1
 // RUN: FileCheck %s --check-prefix=CHECK-UAD-OFF < %t.out
 
 #include <sanitizer/msan_interface.h>