Index: compiler-rt/trunk/lib/lsan/lsan_common_mac.cc
===================================================================
--- compiler-rt/trunk/lib/lsan/lsan_common_mac.cc
+++ compiler-rt/trunk/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: compiler-rt/trunk/lib/lsan/lsan_flags.inc
===================================================================
--- compiler-rt/trunk/lib/lsan/lsan_flags.inc
+++ compiler-rt/trunk/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().")