Index: compiler-rt/CMakeLists.txt
===================================================================
--- compiler-rt/CMakeLists.txt
+++ compiler-rt/CMakeLists.txt
@@ -129,6 +129,7 @@
 if ("${COMPILER_RT_DEFAULT_TARGET_TRIPLE}" MATCHES ".*hf$")
   if (${COMPILER_RT_DEFAULT_TARGET_ARCH} MATCHES "^arm")
     set(COMPILER_RT_DEFAULT_TARGET_ARCH "armhf")
+    CHECK_SYMBOL_EXISTS (__thumb__ "" COMPILER_RT_ARM_THUMB)
   endif()
 endif()
 if ("${COMPILER_RT_DEFAULT_TARGET_TRIPLE}" MATCHES ".*android.*")
Index: compiler-rt/lib/sanitizer_common/sanitizer_platform.h
===================================================================
--- compiler-rt/lib/sanitizer_common/sanitizer_platform.h
+++ compiler-rt/lib/sanitizer_common/sanitizer_platform.h
@@ -197,8 +197,12 @@
 
 #if defined(__arm__)
 # define SANITIZER_ARM 1
+# ifdef __thumb__
+#  define SANITIZER_ARM_THUMB 1
+# endif
 #else
 # define SANITIZER_ARM 0
+# define SANITIZER_ARM_THUMB 0
 #endif
 
 #if SANITIZER_SOLARIS && SANITIZER_WORDSIZE == 32
@@ -318,7 +322,7 @@
 // pthread_exit() performs unwinding that leads to dlopen'ing libgcc_s.so.
 // dlopen mallocs "libgcc_s.so" string which confuses LSan, it fails to realize
 // that this allocation happens in dynamic linker and should be ignored.
-#if SANITIZER_PPC || defined(__thumb__)
+#if SANITIZER_PPC || SANITIZER_ARM_THUMB
 # define SANITIZER_SUPPRESS_LEAK_ON_PTHREAD_EXIT 1
 #else
 # define SANITIZER_SUPPRESS_LEAK_ON_PTHREAD_EXIT 0
Index: compiler-rt/lib/sanitizer_common/sanitizer_stacktrace.h
===================================================================
--- compiler-rt/lib/sanitizer_common/sanitizer_stacktrace.h
+++ compiler-rt/lib/sanitizer_common/sanitizer_stacktrace.h
@@ -22,6 +22,8 @@
 
 #if SANITIZER_LINUX && defined(__mips__)
 # define SANITIZER_CAN_FAST_UNWIND 0
+#elif SANITIZER_LINUX && !SANITIZER_ANDROID && SANITIZER_ARM_THUMB
+# define SANITIZER_CAN_FAST_UNWIND 0
 #elif SANITIZER_WINDOWS
 # define SANITIZER_CAN_FAST_UNWIND 0
 #elif SANITIZER_OPENBSD
Index: compiler-rt/test/asan/TestCases/Linux/quarantine_size_mb.cpp
===================================================================
--- compiler-rt/test/asan/TestCases/Linux/quarantine_size_mb.cpp
+++ compiler-rt/test/asan/TestCases/Linux/quarantine_size_mb.cpp
@@ -1,10 +1,10 @@
 // Test quarantine_size_mb (and the deprecated quarantine_size)
 // RUN: %clangxx_asan  %s -o %t
-// RUN: %env_asan_opts=quarantine_size=10485760:verbosity=1:hard_rss_limit_mb=50 %run %t  2>&1 | FileCheck %s  --check-prefix=Q10
-// RUN: %env_asan_opts=quarantine_size_mb=10:verbosity=1:hard_rss_limit_mb=50    %run %t  2>&1 | FileCheck %s  --check-prefix=Q10
-// RUN: %env_asan_opts=quarantine_size_mb=10:quarantine_size=20:verbosity=1  not %run %t  2>&1 | FileCheck %s  --check-prefix=BOTH
-// RUN: %env_asan_opts=quarantine_size_mb=1000:hard_rss_limit_mb=50 not  %run %t          2>&1 | FileCheck %s  --check-prefix=RSS_LIMIT
-// RUN: %env_asan_opts=hard_rss_limit_mb=20                         not  %run %t          2>&1 | FileCheck %s  --check-prefix=RSS_LIMIT
+// RUN: %env_asan_opts=quarantine_size=10485760:verbosity=1:hard_rss_limit_mb=50:fast_unwind_on_malloc=0 %run %t  2>&1 | FileCheck %s  --check-prefix=Q10
+// RUN: %env_asan_opts=quarantine_size_mb=10:verbosity=1:hard_rss_limit_mb=50:fast_unwind_on_malloc=0    %run %t  2>&1 | FileCheck %s  --check-prefix=Q10
+// RUN: %env_asan_opts=quarantine_size_mb=10:quarantine_size=20:verbosity=1  not %run %t                          2>&1 | FileCheck %s  --check-prefix=BOTH
+// RUN: %env_asan_opts=quarantine_size_mb=1000:hard_rss_limit_mb=50 not  %run %t                                  2>&1 | FileCheck %s  --check-prefix=RSS_LIMIT
+// RUN: %env_asan_opts=hard_rss_limit_mb=20                         not  %run %t                                  2>&1 | FileCheck %s  --check-prefix=RSS_LIMIT
 
 // https://github.com/google/sanitizers/issues/981
 // UNSUPPORTED: android-26
Index: compiler-rt/test/asan/lit.cfg.py
===================================================================
--- compiler-rt/test/asan/lit.cfg.py
+++ compiler-rt/test/asan/lit.cfg.py
@@ -191,7 +191,7 @@
 config.available_features.add("asan-" + config.bits + "-bits")
 
 # Fast unwinder doesn't work with Thumb
-if re.search('mthumb', config.target_cflags) is None:
+if not config.arm_thumb:
   config.available_features.add('fast-unwinder-works')
 
 # Turn on leak detection on 64-bit Linux.
Index: compiler-rt/test/asan/lit.site.cfg.py.in
===================================================================
--- compiler-rt/test/asan/lit.site.cfg.py.in
+++ compiler-rt/test/asan/lit.site.cfg.py.in
@@ -5,6 +5,7 @@
 config.target_cflags = "@ASAN_TEST_TARGET_CFLAGS@"
 config.clang = "@ASAN_TEST_TARGET_CC@"
 config.bits = "@ASAN_TEST_BITS@"
+config.arm_thumb = "@COMPILER_RT_ARM_THUMB@"
 config.apple_platform = "@ASAN_TEST_APPLE_PLATFORM@"
 config.apple_platform_min_deployment_target_flag = "@ASAN_TEST_MIN_DEPLOYMENT_TARGET_FLAG@"
 config.asan_dynamic = @ASAN_TEST_DYNAMIC@