Index: compiler-rt/CMakeLists.txt
===================================================================
--- compiler-rt/CMakeLists.txt
+++ compiler-rt/CMakeLists.txt
@@ -114,6 +114,7 @@
 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_flags.inc
===================================================================
--- compiler-rt/lib/sanitizer_common/sanitizer_flags.inc
+++ compiler-rt/lib/sanitizer_common/sanitizer_flags.inc
@@ -40,7 +40,12 @@
 COMMON_FLAG(bool, fast_unwind_on_fatal, false,
             "If available, use the fast frame-pointer-based unwinder on fatal "
             "errors.")
-COMMON_FLAG(bool, fast_unwind_on_malloc, true,
+// ARM thumb/thumb2 frame pointer is inconsistent on GCC and Clang [1]
+// and fast-unwider is also unreliable with mixing arm and thumb code [2].
+// [1] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92172
+// [2] https://bugs.llvm.org/show_bug.cgi?id=44158
+COMMON_FLAG(bool, fast_unwind_on_malloc,
+	    !(SANITIZER_LINUX && !SANITIZER_ANDROID && SANITIZER_ARM),
             "If available, use the fast frame-pointer-based unwinder on "
             "malloc/free.")
 COMMON_FLAG(bool, handle_ioctl, false, "Intercept and handle ioctl requests.")
Index: compiler-rt/test/asan/TestCases/Linux/clang_gcc_abi.cpp
===================================================================
--- compiler-rt/test/asan/TestCases/Linux/clang_gcc_abi.cpp
+++ compiler-rt/test/asan/TestCases/Linux/clang_gcc_abi.cpp
@@ -1,7 +1,7 @@
-// RUN: %clangxx_asan -O0 -x c %s -o %t && not %run %t 2>&1 | FileCheck %s
-// RUN: %clangxx_asan -O1 -x c %s -o %t && not %run %t 2>&1 | FileCheck %s
-// RUN: %clangxx_asan -O2 -x c %s -o %t && not %run %t 2>&1 | FileCheck %s
-// RUN: %clangxx_asan -O3 -x c %s -o %t && not %run %t 2>&1 | FileCheck %s
+// RUN: %clangxx_asan -O0 -x c %s -o %t && not %env_asan_opts=fast_unwind_on_malloc=1 %run %t 2>&1 | FileCheck %s
+// RUN: %clangxx_asan -O1 -x c %s -o %t && not %env_asan_opts=fast_unwind_on_malloc=1 %run %t 2>&1 | FileCheck %s
+// RUN: %clangxx_asan -O2 -x c %s -o %t && not %env_asan_opts=fast_unwind_on_malloc=1 %run %t 2>&1 | FileCheck %s
+// RUN: %clangxx_asan -O3 -x c %s -o %t && not %env_asan_opts=fast_unwind_on_malloc=1 %run %t 2>&1 | FileCheck %s
 
 // REQUIRES: (arm-target-arch || armhf-target-arch), fast-unwinder-works
 
Index: compiler-rt/test/asan/lit.cfg.py
===================================================================
--- compiler-rt/test/asan/lit.cfg.py
+++ compiler-rt/test/asan/lit.cfg.py
@@ -205,7 +205,7 @@
 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@