diff --git a/libcxx/cmake/caches/Generic-debug-iterators.cmake b/libcxx/cmake/caches/Generic-debug-iterators.cmake
--- a/libcxx/cmake/caches/Generic-debug-iterators.cmake
+++ b/libcxx/cmake/caches/Generic-debug-iterators.cmake
@@ -1,2 +1,2 @@
-set(LIBCXX_TEST_PARAMS "debug_level=1" "additional_features=LIBCXX-DEBUG-FIXME" CACHE STRING "")
+set(LIBCXX_TEST_PARAMS "debug_level=1" CACHE STRING "")
 set(LIBCXXABI_TEST_PARAMS "${LIBCXX_TEST_PARAMS}" CACHE STRING "")
diff --git a/libcxx/utils/libcxx/test/params.py b/libcxx/utils/libcxx/test/params.py
--- a/libcxx/utils/libcxx/test/params.py
+++ b/libcxx/utils/libcxx/test/params.py
@@ -125,7 +125,8 @@
             help="The debugging level to enable in the test suite.",
             actions=lambda debugLevel: [] if debugLevel == '' else [
               AddFeature('debug_level={}'.format(debugLevel)),
-              AddCompileFlag('-D_LIBCPP_DEBUG={}'.format(debugLevel))
+              AddCompileFlag('-D_LIBCPP_DEBUG={}'.format(debugLevel)),
+              AddFeature('LIBCXX-DEBUG-FIXME') if debugLevel == '1'
             ]),
 
   Parameter(name='use_sanitizer', choices=['', 'Address', 'Undefined', 'Memory', 'MemoryWithOrigins', 'Thread', 'DataFlow', 'Leaks'], type=str, default='',