diff --git a/compiler-rt/test/asan/Unit/lit.site.cfg.py.in b/compiler-rt/test/asan/Unit/lit.site.cfg.py.in
--- a/compiler-rt/test/asan/Unit/lit.site.cfg.py.in
+++ b/compiler-rt/test/asan/Unit/lit.site.cfg.py.in
@@ -62,5 +62,5 @@
 # Set LD_LIBRARY_PATH to pick dynamic runtime up properly.
 push_ld_library_path(config, config.compiler_rt_libdir)
 
-if config.host_os == 'Darwin':
-  config.parallelism_group = config.darwin_sanitizer_parallelism_group_func
+if not config.parallelism_group:
+  config.parallelism_group = 'shadow-memory'
diff --git a/compiler-rt/test/lit.common.cfg.py b/compiler-rt/test/lit.common.cfg.py
--- a/compiler-rt/test/lit.common.cfg.py
+++ b/compiler-rt/test/lit.common.cfg.py
@@ -613,8 +613,8 @@
   # Only run up to 3 processes that require shadow memory simultaneously on
   # 64-bit Darwin. Using more scales badly and hogs the system due to
   # inefficient handling of large mmap'd regions (terabytes) by the kernel.
-  elif config.target_arch in ['x86_64', 'x86_64h']:
-    lit_config.warning('Throttling sanitizer tests that require shadow memory on Darwin 64bit')
+  else:
+    lit_config.warning('Throttling sanitizer tests that require shadow memory on Darwin')
     lit_config.parallelism_groups['shadow-memory'] = 3
 
 # Multiple substitutions are necessary to support multiple shared objects used
diff --git a/compiler-rt/test/sanitizer_common/Unit/lit.site.cfg.py.in b/compiler-rt/test/sanitizer_common/Unit/lit.site.cfg.py.in
--- a/compiler-rt/test/sanitizer_common/Unit/lit.site.cfg.py.in
+++ b/compiler-rt/test/sanitizer_common/Unit/lit.site.cfg.py.in
@@ -13,5 +13,5 @@
                                      "sanitizer_common", "tests")
 config.test_source_root = config.test_exec_root
 
-if config.host_os == 'Darwin':
-  config.parallelism_group = config.darwin_sanitizer_parallelism_group_func
+if not config.parallelism_group:
+  config.parallelism_group = 'shadow-memory'
diff --git a/compiler-rt/test/tsan/Unit/lit.site.cfg.py.in b/compiler-rt/test/tsan/Unit/lit.site.cfg.py.in
--- a/compiler-rt/test/tsan/Unit/lit.site.cfg.py.in
+++ b/compiler-rt/test/tsan/Unit/lit.site.cfg.py.in
@@ -12,9 +12,10 @@
 config.test_exec_root = "@COMPILER_RT_BINARY_DIR@/lib/tsan/tests"
 config.test_source_root = config.test_exec_root
 
-if config.host_os == 'Darwin':
-  config.parallelism_group = config.darwin_sanitizer_parallelism_group_func
+if not config.parallelism_group:
+  config.parallelism_group = 'shadow-memory'
 
+if config.host_os == 'Darwin':
   # On Darwin, we default to ignore_noninstrumented_modules=1, which also
   # suppresses some races the tests are supposed to find.  See tsan/lit.cfg.py.
   if 'TSAN_OPTIONS' in config.environment:
diff --git a/compiler-rt/unittests/lit.common.unit.cfg.py b/compiler-rt/unittests/lit.common.unit.cfg.py
--- a/compiler-rt/unittests/lit.common.unit.cfg.py
+++ b/compiler-rt/unittests/lit.common.unit.cfg.py
@@ -50,13 +50,3 @@
   #
   # rdar://80086125
   config.environment['MallocNanoZone'] = '0'
-
-  # The test config gets pickled and sent to multiprocessing workers, and that
-  # only works for code if it is stored at the top level of some module.
-  # Therefore, we have to put the code in a .py file, add it to path, and import
-  # it to store it in the config.
-  import site
-  site.addsitedir(os.path.dirname(__file__))
-  import lit_unittest_cfg_utils
-  config.darwin_sanitizer_parallelism_group_func = \
-    lit_unittest_cfg_utils.darwin_sanitizer_parallelism_group_func
diff --git a/compiler-rt/unittests/lit_unittest_cfg_utils.py b/compiler-rt/unittests/lit_unittest_cfg_utils.py
deleted file mode 100644
--- a/compiler-rt/unittests/lit_unittest_cfg_utils.py
+++ /dev/null
@@ -1,4 +0,0 @@
-# Put all 64-bit tests in the shadow-memory parallelism group. We throttle those
-# in our common lit config (lit.common.unit.cfg.py).
-def darwin_sanitizer_parallelism_group_func(test):
-  return "shadow-memory" if "x86_64" in test.file_path else None