Index: lib/lsan/lsan_common_mac.cc
===================================================================
--- lib/lsan/lsan_common_mac.cc
+++ lib/lsan/lsan_common_mac.cc
@@ -87,7 +87,12 @@
 
 // Required on Linux for initialization of TLS behavior, but should not be
 // required on Darwin.
-void InitializePlatformSpecificModules() {}
+void InitializePlatformSpecificModules() {
+  if (flags()->use_tls) {
+    Report("use_tls=1 is not supported on Darwin.\n");
+    Die();
+  }
+}
 
 // Scans global variables for heap pointers.
 void ProcessGlobalRegions(Frontier *frontier) {
Index: lib/lsan/lsan_flags.inc
===================================================================
--- lib/lsan/lsan_flags.inc
+++ lib/lsan/lsan_flags.inc
@@ -30,7 +30,7 @@
           "Root set: include global variables (.data and .bss)")
 LSAN_FLAG(bool, use_stacks, true, "Root set: include thread stacks")
 LSAN_FLAG(bool, use_registers, true, "Root set: include thread registers")
-LSAN_FLAG(bool, use_tls, true,
+LSAN_FLAG(bool, use_tls, !SANITIZER_MAC,
           "Root set: include TLS and thread-specific storage")
 LSAN_FLAG(bool, use_root_regions, true,
           "Root set: include regions added via __lsan_register_root_region().")
Index: test/lsan/TestCases/cleanup_in_tsd_destructor.c
===================================================================
--- test/lsan/TestCases/cleanup_in_tsd_destructor.c
+++ test/lsan/TestCases/cleanup_in_tsd_destructor.c
@@ -7,6 +7,9 @@
 // RUN: %clang_lsan %s -o %t
 // RUN: LSAN_OPTIONS=$LSAN_BASE:use_tls=1 %run %t
 // RUN: LSAN_OPTIONS=$LSAN_BASE:use_tls=0 not %run %t 2>&1 | FileCheck %s
+//
+// OS X doesn't support tls
+// UNSUPPORTED: darwin
 
 #include <assert.h>
 #include <pthread.h>
Index: test/lsan/TestCases/disabler_in_tsd_destructor.c
===================================================================
--- test/lsan/TestCases/disabler_in_tsd_destructor.c
+++ test/lsan/TestCases/disabler_in_tsd_destructor.c
@@ -2,6 +2,9 @@
 // RUN: LSAN_BASE="report_objects=1:use_registers=0:use_stacks=0:use_globals=0:use_tls=1:use_ld_allocations=0"
 // RUN: %clang_lsan %s -o %t
 // RUN: LSAN_OPTIONS=$LSAN_BASE %run %t
+//
+// OS X doesn't support tls
+// UNSUPPORTED: darwin
 
 #include <assert.h>
 #include <pthread.h>
Index: test/lsan/TestCases/use_tls_dynamic.cc
===================================================================
--- test/lsan/TestCases/use_tls_dynamic.cc
+++ test/lsan/TestCases/use_tls_dynamic.cc
@@ -5,7 +5,7 @@
 // RUN: LSAN_OPTIONS=$LSAN_BASE:"use_tls=0" not %run %t 2>&1 | FileCheck %s
 // RUN: LSAN_OPTIONS=$LSAN_BASE:"use_tls=1" %run %t 2>&1
 // RUN: LSAN_OPTIONS="" %run %t 2>&1
-// UNSUPPORTED: i386-linux,i686-linux,arm
+// UNSUPPORTED: i386-linux,i686-linux,arm,darwin
 
 #ifndef BUILD_DSO
 #include <assert.h>
Index: test/lsan/TestCases/use_tls_pthread_specific_dynamic.cc
===================================================================
--- test/lsan/TestCases/use_tls_pthread_specific_dynamic.cc
+++ test/lsan/TestCases/use_tls_pthread_specific_dynamic.cc
@@ -4,6 +4,9 @@
 // RUN: LSAN_OPTIONS=$LSAN_BASE:"use_tls=0" not %run %t 2>&1 | FileCheck %s
 // RUN: LSAN_OPTIONS=$LSAN_BASE:"use_tls=1" %run %t 2>&1
 // RUN: LSAN_OPTIONS="" %run %t 2>&1
+//
+// OS X doesn't support tls
+// UNSUPPORTED: darwin
 
 #include <assert.h>
 #include <pthread.h>
Index: test/lsan/TestCases/use_tls_pthread_specific_static.cc
===================================================================
--- test/lsan/TestCases/use_tls_pthread_specific_static.cc
+++ test/lsan/TestCases/use_tls_pthread_specific_static.cc
@@ -4,6 +4,9 @@
 // RUN: LSAN_OPTIONS=$LSAN_BASE:"use_tls=0" not %run %t 2>&1 | FileCheck %s
 // RUN: LSAN_OPTIONS=$LSAN_BASE:"use_tls=1" %run %t 2>&1
 // RUN: LSAN_OPTIONS="" %run %t 2>&1
+//
+// OS X doesn't support tls
+// UNSUPPORTED: darwin
 
 #include <assert.h>
 #include <pthread.h>
Index: test/lsan/TestCases/use_tls_static.cc
===================================================================
--- test/lsan/TestCases/use_tls_static.cc
+++ test/lsan/TestCases/use_tls_static.cc
@@ -4,6 +4,9 @@
 // RUN: LSAN_OPTIONS=$LSAN_BASE:"use_tls=0" not %run %t 2>&1 | FileCheck %s
 // RUN: LSAN_OPTIONS=$LSAN_BASE:"use_tls=1" %run %t 2>&1
 // RUN: LSAN_OPTIONS="" %run %t 2>&1
+//
+// OS X doesn't support tls
+// UNSUPPORTED: darwin
 
 #include <stdio.h>
 #include <stdlib.h>