diff --git a/tests/Android.mk b/tests/Android.mk
index 8f2d3cf..e2fae52 100644
--- a/tests/Android.mk
+++ b/tests/Android.mk
@@ -313,15 +313,6 @@
     libdl_preempt_test_1 \
     libdl_preempt_test_2
 
-# Clang/llvm has incompatible long double (fp128) for x86_64.
-# https://llvm.org/bugs/show_bug.cgi?id=23897
-# This affects most of math_test.cpp.
-# For arm and arm64 target, b/25643775:
-# external/libcxx/include/sstream:859: warning: relocation refers to discarded section
-ifeq ($(TARGET_ARCH),$(filter $(TARGET_ARCH),x86_64 arm arm64))
-bionic-unit-tests_clang_target := false
-endif
-
 bionic-unit-tests_shared_libraries_target += libdl_test_df_1_global
 
 module := bionic-unit-tests
diff --git a/tests/atexit_test.cpp b/tests/atexit_test.cpp
index e92889d..67fbfd2 100644
--- a/tests/atexit_test.cpp
+++ b/tests/atexit_test.cpp
@@ -14,7 +14,17 @@
  * limitations under the License.
  */
 
+// To work around b/25643775, we disable clang optimization so that
+//   VTT for std::__1::basic_stringstream<char, std::__1::char_traits<char>,
+//   std::__1::allocator<char> >
+// will be correctly kept for other module's references.
+#if defined(__clang__) && (defined(__arm__) || defined(__aarch64__))
+#pragma clang optimize off
+#endif
 #include <gtest/gtest.h>
+#if defined(__clang__) && (defined(__arm__) || defined(__aarch64__))
+#pragma clang optimize on
+#endif
 
 #include <dlfcn.h>
 #include <libgen.h>