Index: compiler-rt/trunk/test/tsan/Darwin/symbolizer-atos.cc
===================================================================
--- compiler-rt/trunk/test/tsan/Darwin/symbolizer-atos.cc
+++ compiler-rt/trunk/test/tsan/Darwin/symbolizer-atos.cc
@@ -1,5 +1,5 @@
 // RUN: %clangxx_tsan %s -o %t
-// RUN: TSAN_OPTIONS=$TSAN_OPTIONS:verbosity=2:external_symbolizer_path=/usr/bin/atos %deflake %run %t | FileCheck %s
+// RUN: %env_tsan_opts=verbosity=2:external_symbolizer_path=/usr/bin/atos %deflake %run %t | FileCheck %s
 #include "../test.h"
 
 int GlobalData[10];
Index: compiler-rt/trunk/test/tsan/Darwin/symbolizer-dladdr.cc
===================================================================
--- compiler-rt/trunk/test/tsan/Darwin/symbolizer-dladdr.cc
+++ compiler-rt/trunk/test/tsan/Darwin/symbolizer-dladdr.cc
@@ -1,5 +1,5 @@
 // RUN: %clangxx_tsan %s -o %t
-// RUN: TSAN_OPTIONS=$TSAN_OPTIONS:verbosity=2:external_symbolizer_path= %deflake %run %t | FileCheck %s
+// RUN: %env_tsan_opts=verbosity=2:external_symbolizer_path= %deflake %run %t | FileCheck %s
 #include "../test.h"
 
 int GlobalData[10];
Index: compiler-rt/trunk/test/tsan/allocator_returns_null.cc
===================================================================
--- compiler-rt/trunk/test/tsan/allocator_returns_null.cc
+++ compiler-rt/trunk/test/tsan/allocator_returns_null.cc
@@ -4,11 +4,11 @@
 //
 // RUN: %clangxx_tsan -O0 %s -o %t
 // RUN: not %run %t malloc 2>&1 | FileCheck %s --check-prefix=CHECK-mCRASH
-// RUN: TSAN_OPTIONS=allocator_may_return_null=0 not %run %t malloc 2>&1 | FileCheck %s --check-prefix=CHECK-mCRASH
-// RUN: TSAN_OPTIONS=allocator_may_return_null=0 not %run %t calloc 2>&1 | FileCheck %s --check-prefix=CHECK-cCRASH
-// RUN: TSAN_OPTIONS=allocator_may_return_null=0 not %run %t calloc-overflow 2>&1 | FileCheck %s --check-prefix=CHECK-coCRASH
-// RUN: TSAN_OPTIONS=allocator_may_return_null=0 not %run %t realloc 2>&1 | FileCheck %s --check-prefix=CHECK-rCRASH
-// RUN: TSAN_OPTIONS=allocator_may_return_null=0 not %run %t realloc-after-malloc 2>&1 | FileCheck %s --check-prefix=CHECK-mrCRASH
+// RUN: %env_tsan_opts=allocator_may_return_null=0 not %run %t malloc 2>&1 | FileCheck %s --check-prefix=CHECK-mCRASH
+// RUN: %env_tsan_opts=allocator_may_return_null=0 not %run %t calloc 2>&1 | FileCheck %s --check-prefix=CHECK-cCRASH
+// RUN: %env_tsan_opts=allocator_may_return_null=0 not %run %t calloc-overflow 2>&1 | FileCheck %s --check-prefix=CHECK-coCRASH
+// RUN: %env_tsan_opts=allocator_may_return_null=0 not %run %t realloc 2>&1 | FileCheck %s --check-prefix=CHECK-rCRASH
+// RUN: %env_tsan_opts=allocator_may_return_null=0 not %run %t realloc-after-malloc 2>&1 | FileCheck %s --check-prefix=CHECK-mrCRASH
 
 #include <limits.h>
 #include <stdlib.h>
Index: compiler-rt/trunk/test/tsan/deadlock_detector_stress_test.cc
===================================================================
--- compiler-rt/trunk/test/tsan/deadlock_detector_stress_test.cc
+++ compiler-rt/trunk/test/tsan/deadlock_detector_stress_test.cc
@@ -1,12 +1,12 @@
 // RUN: %clangxx_tsan %s -o %t -DLockType=PthreadMutex
-// RUN: TSAN_OPTIONS=detect_deadlocks=1 %deflake %run %t | FileCheck %s --check-prefix=CHECK --check-prefix=CHECK-NOT-SECOND
-// RUN: TSAN_OPTIONS="detect_deadlocks=1 second_deadlock_stack=1" %deflake %run %t | FileCheck %s --check-prefix=CHECK --check-prefix=CHECK-SECOND
+// RUN: %env_tsan_opts=detect_deadlocks=1 %deflake %run %t | FileCheck %s --check-prefix=CHECK --check-prefix=CHECK-NOT-SECOND
+// RUN: %env_tsan_opts=detect_deadlocks=1:second_deadlock_stack=1 %deflake %run %t | FileCheck %s --check-prefix=CHECK --check-prefix=CHECK-SECOND
 // RUN: %clangxx_tsan %s -o %t -DLockType=PthreadSpinLock
-// RUN: TSAN_OPTIONS=detect_deadlocks=1 %deflake %run %t | FileCheck %s
+// RUN: %env_tsan_opts=detect_deadlocks=1 %deflake %run %t | FileCheck %s
 // RUN: %clangxx_tsan %s -o %t -DLockType=PthreadRWLock
-// RUN: TSAN_OPTIONS=detect_deadlocks=1 %deflake %run %t | FileCheck %s --check-prefix=CHECK --check-prefix=CHECK-RD
+// RUN: %env_tsan_opts=detect_deadlocks=1 %deflake %run %t | FileCheck %s --check-prefix=CHECK --check-prefix=CHECK-RD
 // RUN: %clangxx_tsan %s -o %t -DLockType=PthreadRecursiveMutex
-// RUN: TSAN_OPTIONS=detect_deadlocks=1 %deflake %run %t | FileCheck %s --check-prefix=CHECK --check-prefix=CHECK-REC
+// RUN: %env_tsan_opts=detect_deadlocks=1 %deflake %run %t | FileCheck %s --check-prefix=CHECK --check-prefix=CHECK-REC
 #include "test.h"
 #undef NDEBUG
 #include <assert.h>
Index: compiler-rt/trunk/test/tsan/fork_atexit.cc
===================================================================
--- compiler-rt/trunk/test/tsan/fork_atexit.cc
+++ compiler-rt/trunk/test/tsan/fork_atexit.cc
@@ -1,4 +1,4 @@
-// RUN: %clangxx_tsan -O1 %s -o %t && TSAN_OPTIONS="atexit_sleep_ms=50" %run %t 2>&1 | FileCheck %s
+// RUN: %clangxx_tsan -O1 %s -o %t && %env_tsan_opts=atexit_sleep_ms=50 %run %t 2>&1 | FileCheck %s
 // UNSUPPORTED: darwin
 #include <pthread.h>
 #include <stdio.h>
Index: compiler-rt/trunk/test/tsan/fork_deadlock.cc
===================================================================
--- compiler-rt/trunk/test/tsan/fork_deadlock.cc
+++ compiler-rt/trunk/test/tsan/fork_deadlock.cc
@@ -1,4 +1,4 @@
-// RUN: %clangxx_tsan -O1 %s -o %t && TSAN_OPTIONS="atexit_sleep_ms=50" %run %t 2>&1 | FileCheck %s
+// RUN: %clangxx_tsan -O1 %s -o %t && %env_tsan_opts=atexit_sleep_ms=50 %run %t 2>&1 | FileCheck %s
 // UNSUPPORTED: darwin
 #include "test.h"
 #include <errno.h>
Index: compiler-rt/trunk/test/tsan/fork_multithreaded.cc
===================================================================
--- compiler-rt/trunk/test/tsan/fork_multithreaded.cc
+++ compiler-rt/trunk/test/tsan/fork_multithreaded.cc
@@ -1,5 +1,5 @@
 // RUN: %clangxx_tsan -O1 %s -o %t && %run %t 2>&1 | FileCheck %s -check-prefix=CHECK-DIE
-// RUN: %clangxx_tsan -O1 %s -o %t && TSAN_OPTIONS="die_after_fork=0" %run %t 2>&1 | FileCheck %s -check-prefix=CHECK-NODIE
+// RUN: %clangxx_tsan -O1 %s -o %t && %env_tsan_opts=die_after_fork=0 %run %t 2>&1 | FileCheck %s -check-prefix=CHECK-NODIE
 // UNSUPPORTED: darwin
 #include "test.h"
 #include <errno.h>
Index: compiler-rt/trunk/test/tsan/free_race.c
===================================================================
--- compiler-rt/trunk/test/tsan/free_race.c
+++ compiler-rt/trunk/test/tsan/free_race.c
@@ -1,6 +1,6 @@
 // RUN: %clang_tsan -O1 %s -o %t
 // RUN: %deflake %run %t | FileCheck %s --check-prefix=CHECK-NOZUPP
-// RUN: TSAN_OPTIONS="suppressions='%s.supp' print_suppressions=1" %run %t 2>&1 | FileCheck %s --check-prefix=CHECK-SUPP
+// RUN: %env_tsan_opts=suppressions='%s.supp':print_suppressions=1 %run %t 2>&1 | FileCheck %s --check-prefix=CHECK-SUPP
 
 #include "test.h"
 
Index: compiler-rt/trunk/test/tsan/halt_on_error.cc
===================================================================
--- compiler-rt/trunk/test/tsan/halt_on_error.cc
+++ compiler-rt/trunk/test/tsan/halt_on_error.cc
@@ -1,4 +1,4 @@
-// RUN: %clang_tsan -O1 %s -o %t && TSAN_OPTIONS="$TSAN_OPTIONS halt_on_error=1" %deflake %run %t | FileCheck %s
+// RUN: %clang_tsan -O1 %s -o %t && %env_tsan_opts=halt_on_error=1 %deflake %run %t | FileCheck %s
 #include "test.h"
 
 int X;
Index: compiler-rt/trunk/test/tsan/ignore_lib0.cc
===================================================================
--- compiler-rt/trunk/test/tsan/ignore_lib0.cc
+++ compiler-rt/trunk/test/tsan/ignore_lib0.cc
@@ -3,7 +3,7 @@
 // RUN: echo running w/o suppressions:
 // RUN: LD_LIBRARY_PATH=%T${LD_LIBRARY_PATH:+:$LD_LIBRARY_PATH} %deflake %run %t | FileCheck %s --check-prefix=CHECK-NOSUPP
 // RUN: echo running with suppressions:
-// RUN: LD_LIBRARY_PATH=%T${LD_LIBRARY_PATH:+:$LD_LIBRARY_PATH} TSAN_OPTIONS="$TSAN_OPTIONS suppressions='%s.supp'" %run %t 2>&1 | FileCheck %s --check-prefix=CHECK-WITHSUPP
+// RUN: LD_LIBRARY_PATH=%T${LD_LIBRARY_PATH:+:$LD_LIBRARY_PATH} %env_tsan_opts=suppressions='%s.supp' %run %t 2>&1 | FileCheck %s --check-prefix=CHECK-WITHSUPP
 
 // Tests that interceptors coming from a library specified in called_from_lib
 // suppression are ignored.
Index: compiler-rt/trunk/test/tsan/ignore_lib1.cc
===================================================================
--- compiler-rt/trunk/test/tsan/ignore_lib1.cc
+++ compiler-rt/trunk/test/tsan/ignore_lib1.cc
@@ -3,7 +3,7 @@
 // RUN: echo running w/o suppressions:
 // RUN: %deflake %run %t | FileCheck %s --check-prefix=CHECK-NOSUPP
 // RUN: echo running with suppressions:
-// RUN: TSAN_OPTIONS="$TSAN_OPTIONS suppressions='%s.supp'" %run %t 2>&1 | FileCheck %s --check-prefix=CHECK-WITHSUPP
+// RUN: %env_tsan_opts=suppressions='%s.supp' %run %t 2>&1 | FileCheck %s --check-prefix=CHECK-WITHSUPP
 
 // Tests that interceptors coming from a dynamically loaded library specified
 // in called_from_lib suppression are ignored.
Index: compiler-rt/trunk/test/tsan/ignore_lib2.cc
===================================================================
--- compiler-rt/trunk/test/tsan/ignore_lib2.cc
+++ compiler-rt/trunk/test/tsan/ignore_lib2.cc
@@ -1,7 +1,7 @@
 // RUN: %clangxx_tsan -O1 %s -DLIB -fPIC -fno-sanitize=thread -shared -o %T/libignore_lib2_0.so
 // RUN: %clangxx_tsan -O1 %s -DLIB -fPIC -fno-sanitize=thread -shared -o %T/libignore_lib2_1.so
 // RUN: %clangxx_tsan -O1 %s -o %t
-// RUN: TSAN_OPTIONS="$TSAN_OPTIONS suppressions='%s.supp'" %deflake %run %t | FileCheck %s
+// RUN: %env_tsan_opts=suppressions='%s.supp' %deflake %run %t | FileCheck %s
 
 // Tests that called_from_lib suppression matched against 2 libraries
 // causes program crash (this is not supported).
Index: compiler-rt/trunk/test/tsan/ignore_lib3.cc
===================================================================
--- compiler-rt/trunk/test/tsan/ignore_lib3.cc
+++ compiler-rt/trunk/test/tsan/ignore_lib3.cc
@@ -1,6 +1,6 @@
 // RUN: %clangxx_tsan -O1 %s -DLIB -fPIC -fno-sanitize=thread -shared -o %T/libignore_lib3.so
 // RUN: %clangxx_tsan -O1 %s -o %t
-// RUN: TSAN_OPTIONS="$TSAN_OPTIONS suppressions='%s.supp'" %deflake %run %t | FileCheck %s
+// RUN: %env_tsan_opts=suppressions='%s.supp' %deflake %run %t | FileCheck %s
 
 // Tests that unloading of a library matched against called_from_lib suppression
 // causes program crash (this is not supported).
Index: compiler-rt/trunk/test/tsan/lit.cfg
===================================================================
--- compiler-rt/trunk/test/tsan/lit.cfg
+++ compiler-rt/trunk/test/tsan/lit.cfg
@@ -18,14 +18,19 @@
 config.test_source_root = os.path.dirname(__file__)
 
 # Setup environment variables for running ThreadSanitizer.
-tsan_options = "atexit_sleep_ms=0"
+default_tsan_opts = "atexit_sleep_ms=0"
 
 if config.host_os == 'Darwin':
   # On Darwin, we default to `abort_on_error=1`, which would make tests run
   # much slower. Let's override this and run lit tests with 'abort_on_error=0'.
-  tsan_options += ':abort_on_error=0'
+  default_tsan_opts += ':abort_on_error=0'
 
-config.environment['TSAN_OPTIONS'] = tsan_options
+# Platform-specific default TSAN_OPTIONS for lit tests.
+if default_tsan_opts:
+  config.environment['TSAN_OPTIONS'] = default_tsan_opts
+  default_tsan_opts += ':'
+config.substitutions.append(('%env_tsan_opts=',
+                             'env TSAN_OPTIONS=' + default_tsan_opts))
 
 # GCC driver doesn't add necessary compile/link flags with -fsanitize=thread.
 if config.compiler_id == 'GNU':
Index: compiler-rt/trunk/test/tsan/malloc_overflow.cc
===================================================================
--- compiler-rt/trunk/test/tsan/malloc_overflow.cc
+++ compiler-rt/trunk/test/tsan/malloc_overflow.cc
@@ -1,5 +1,5 @@
 // RUN: %clangxx_tsan -O1 %s -o %t
-// RUN: TSAN_OPTIONS=allocator_may_return_null=1 %run %t 2>&1 | FileCheck %s
+// RUN: %env_tsan_opts=allocator_may_return_null=1 %run %t 2>&1 | FileCheck %s
 #include <stdio.h>
 #include <stdlib.h>
 
Index: compiler-rt/trunk/test/tsan/mutex_cycle2.c
===================================================================
--- compiler-rt/trunk/test/tsan/mutex_cycle2.c
+++ compiler-rt/trunk/test/tsan/mutex_cycle2.c
@@ -1,11 +1,11 @@
 // RUN: %clangxx_tsan %s -o %t
 // RUN:                                 not %run %t 2>&1 | FileCheck %s
-// RUN: TSAN_OPTIONS=detect_deadlocks=1 not %run %t 2>&1 | FileCheck %s
-// RUN: TSAN_OPTIONS=detect_deadlocks=0     %run %t 2>&1 | FileCheck %s --check-prefix=DISABLED
+// RUN: %env_tsan_opts=detect_deadlocks=1 not %run %t 2>&1 | FileCheck %s
+// RUN: %env_tsan_opts=detect_deadlocks=0     %run %t 2>&1 | FileCheck %s --check-prefix=DISABLED
 // RUN: echo "deadlock:main" > %t.supp
-// RUN: TSAN_OPTIONS="suppressions='%t.supp'" %run %t 2>&1 | FileCheck %s --check-prefix=DISABLED
+// RUN: %env_tsan_opts=suppressions='%t.supp' %run %t 2>&1 | FileCheck %s --check-prefix=DISABLED
 // RUN: echo "deadlock:zzzz" > %t.supp
-// RUN: TSAN_OPTIONS="suppressions='%t.supp'" not %run %t 2>&1 | FileCheck %s
+// RUN: %env_tsan_opts=suppressions='%t.supp' not %run %t 2>&1 | FileCheck %s
 #include <pthread.h>
 #include <stdio.h>
 
Index: compiler-rt/trunk/test/tsan/race_top_suppression.cc
===================================================================
--- compiler-rt/trunk/test/tsan/race_top_suppression.cc
+++ compiler-rt/trunk/test/tsan/race_top_suppression.cc
@@ -1,6 +1,6 @@
 // RUN: echo "race_top:TopFunction" > %t.supp
 // RUN: %clangxx_tsan -O1 %s -o %t
-// RUN: TSAN_OPTIONS="$TSAN_OPTIONS suppressions='%t.supp'" %run %t 2>&1 | FileCheck %s
+// RUN: %env_tsan_opts=suppressions='%t.supp' %run %t 2>&1 | FileCheck %s
 // RUN: rm %t.supp
 #include "test.h"
 
Index: compiler-rt/trunk/test/tsan/race_top_suppression1.cc
===================================================================
--- compiler-rt/trunk/test/tsan/race_top_suppression1.cc
+++ compiler-rt/trunk/test/tsan/race_top_suppression1.cc
@@ -1,6 +1,6 @@
 // RUN: echo "race_top:TopFunction" > %t.supp
 // RUN: %clangxx_tsan -O1 %s -o %t
-// RUN: TSAN_OPTIONS="$TSAN_OPTIONS suppressions='%t.supp'" %deflake %run %t 2>&1 | FileCheck %s
+// RUN: %env_tsan_opts=suppressions='%t.supp' %deflake %run %t 2>&1 | FileCheck %s
 // RUN: rm %t.supp
 #include "test.h"
 
Index: compiler-rt/trunk/test/tsan/setuid2.c
===================================================================
--- compiler-rt/trunk/test/tsan/setuid2.c
+++ compiler-rt/trunk/test/tsan/setuid2.c
@@ -1,4 +1,4 @@
-// RUN: %clang_tsan -O1 %s -o %t && TSAN_OPTIONS="flush_memory_ms=1 memory_limit_mb=1" %run %t 2>&1 | FileCheck %s
+// RUN: %clang_tsan -O1 %s -o %t && %env_tsan_opts=flush_memory_ms=1:memory_limit_mb=1 %run %t 2>&1 | FileCheck %s
 #include "test.h"
 #include <sys/types.h>
 #include <unistd.h>
Index: compiler-rt/trunk/test/tsan/suppressions_global.cc
===================================================================
--- compiler-rt/trunk/test/tsan/suppressions_global.cc
+++ compiler-rt/trunk/test/tsan/suppressions_global.cc
@@ -1,4 +1,4 @@
-// RUN: %clang_tsan -O1 %s -o %t && TSAN_OPTIONS="$TSAN_OPTIONS suppressions='%s.supp'" %run %t 2>&1 | FileCheck %s
+// RUN: %clang_tsan -O1 %s -o %t && %env_tsan_opts=suppressions='%s.supp' %run %t 2>&1 | FileCheck %s
 #include <pthread.h>
 #include <stdio.h>
 
Index: compiler-rt/trunk/test/tsan/suppressions_race.cc
===================================================================
--- compiler-rt/trunk/test/tsan/suppressions_race.cc
+++ compiler-rt/trunk/test/tsan/suppressions_race.cc
@@ -1,4 +1,4 @@
-// RUN: %clang_tsan -O1 %s -o %t && TSAN_OPTIONS="$TSAN_OPTIONS suppressions='%s.supp'" %run %t 2>&1 | FileCheck %s
+// RUN: %clang_tsan -O1 %s -o %t && %env_tsan_opts=suppressions='%s.supp' %run %t 2>&1 | FileCheck %s
 #include "test.h"
 
 int Global;
Index: compiler-rt/trunk/test/tsan/suppressions_race2.cc
===================================================================
--- compiler-rt/trunk/test/tsan/suppressions_race2.cc
+++ compiler-rt/trunk/test/tsan/suppressions_race2.cc
@@ -1,4 +1,4 @@
-// RUN: %clang_tsan -O1 %s -o %t && TSAN_OPTIONS="$TSAN_OPTIONS suppressions='%s.supp'" %run %t 2>&1 | FileCheck %s
+// RUN: %clang_tsan -O1 %s -o %t && %env_tsan_opts=suppressions='%s.supp' %run %t 2>&1 | FileCheck %s
 #include "test.h"
 
 int Global;