diff --git a/compiler-rt/lib/fuzzer/CMakeLists.txt b/compiler-rt/lib/fuzzer/CMakeLists.txt
index a57e2fe46245..2da488d6e57f 100644
--- a/compiler-rt/lib/fuzzer/CMakeLists.txt
+++ b/compiler-rt/lib/fuzzer/CMakeLists.txt
@@ -165,6 +165,7 @@ if(OS_NAME MATCHES "Android|Linux|Fuchsia" AND
                  -DRUNTIMES_EXECUTE_ONLY_CODE=${RUNTIMES_EXECUTE_ONLY_CODE}
                  -DLIBCXXABI_ENABLE_EXCEPTIONS=OFF
                  -DLIBCXX_ABI_NAMESPACE=__Fuzzer
+                 -DLIBCXX_ABI_UNSTABLE=ON
                  -DLIBCXX_ENABLE_EXCEPTIONS=OFF)
     target_compile_options(RTfuzzer.${arch} PRIVATE -isystem ${LIBCXX_${arch}_PREFIX}/include/c++/v1)
     add_dependencies(RTfuzzer.${arch} libcxx_fuzzer_${arch}-install-cmake326-workaround)