diff --git a/libcxx/benchmarks/CMakeLists.txt b/libcxx/benchmarks/CMakeLists.txt
--- a/libcxx/benchmarks/CMakeLists.txt
+++ b/libcxx/benchmarks/CMakeLists.txt
@@ -166,6 +166,11 @@
 # Register Benchmark tests
 #==============================================================================
 file(GLOB BENCHMARK_TESTS "*.bench.cpp")
+
+if (NOT LIBCXX_ENABLE_INCOMPLETE_FEATURES)
+  list(FILTER BENCHMARK_TESTS EXCLUDE REGEX "(format_to_n|format_to|format|formatted_size|formatter_float|std_format_spec_string_unicode).bench.cpp")
+endif()
+
 foreach(test_path ${BENCHMARK_TESTS})
   get_filename_component(test_file "${test_path}" NAME)
   string(REPLACE ".bench.cpp" "" test_name "${test_file}")
diff --git a/libcxx/include/module.modulemap b/libcxx/include/module.modulemap
--- a/libcxx/include/module.modulemap
+++ b/libcxx/include/module.modulemap
@@ -2,7 +2,8 @@
 // since __config may be included from C headers which may create an
 // include cycle.
 module std_config [system] [extern_c] {
-    header "__config"
+  textual header "__config"
+  textual header "__config_site"
 }
 
 module std [system] {
diff --git a/libcxx/utils/libcxx/test/features.py b/libcxx/utils/libcxx/test/features.py
--- a/libcxx/utils/libcxx/test/features.py
+++ b/libcxx/utils/libcxx/test/features.py
@@ -129,22 +129,10 @@
   '_LIBCPP_HAS_NO_UNICODE': 'libcpp-has-no-unicode',
 }
 for macro, feature in macros.items():
-  DEFAULT_FEATURES += [
-    Feature(name=lambda cfg, m=macro, f=feature: f + (
-              '={}'.format(compilerMacros(cfg)[m]) if compilerMacros(cfg)[m] else ''
-            ),
-            when=lambda cfg, m=macro: m in compilerMacros(cfg),
-
-            # FIXME: This is a hack that should be fixed using module maps.
-            # If modules are enabled then we have to lift all of the definitions
-            # in <__config_site> onto the command line.
-            actions=lambda cfg, m=macro: [
-              AddCompileFlag('-Wno-macro-redefined -D{}'.format(m) + (
-                '={}'.format(compilerMacros(cfg)[m]) if compilerMacros(cfg)[m] else ''
-              ))
-            ]
-    )
-  ]
+  DEFAULT_FEATURES.append(
+    Feature(name=lambda cfg, m=macro, f=feature: f + ('={}'.format(compilerMacros(cfg)[m]) if compilerMacros(cfg)[m] else ''),
+            when=lambda cfg, m=macro: m in compilerMacros(cfg))
+  )
 
 
 # Mapping from canonical locale names (used in the tests) to possible locale