diff --git a/compiler-rt/test/asan/lit.cfg b/compiler-rt/test/asan/lit.cfg
--- a/compiler-rt/test/asan/lit.cfg
+++ b/compiler-rt/test/asan/lit.cfg
@@ -220,6 +220,4 @@
 if config.host_os not in ['Linux', 'Darwin', 'FreeBSD', 'SunOS', 'Windows', 'NetBSD']:
   config.unsupported = True
 
-if config.host_os == 'Darwin':
-  if config.target_arch in ["x86_64", "x86_64h"]:
-    config.parallelism_group = "darwin-64bit-sanitizer"
+config.parallelism_group = 'shadow-memory'
diff --git a/compiler-rt/test/fuzzer/lit.cfg b/compiler-rt/test/fuzzer/lit.cfg
--- a/compiler-rt/test/fuzzer/lit.cfg
+++ b/compiler-rt/test/fuzzer/lit.cfg
@@ -126,6 +126,4 @@
 config.substitutions.append(('%env_asan_opts=',
                              'env ASAN_OPTIONS=' + default_asan_opts_str))
 
-if config.host_os == 'Darwin':
-  if config.target_arch in ["x86_64", "x86_64h"]:
-    config.parallelism_group = "darwin-64bit-sanitizer"
+config.parallelism_group = 'shadow-memory'
diff --git a/compiler-rt/test/lit.common.cfg b/compiler-rt/test/lit.common.cfg
--- a/compiler-rt/test/lit.common.cfg
+++ b/compiler-rt/test/lit.common.cfg
@@ -401,17 +401,23 @@
 if platform.system() == 'Windows':
   config.test_retry_attempts = 2
 
-# Only run up to 3 64-bit sanitized processes simultaneously on Darwin.
-# Using more scales badly and hogs the system due to inefficient handling
-# of large mmap'd regions (terabytes) by the kernel.
-if platform.system() == 'Darwin':
-  lit_config.parallelism_groups["darwin-64bit-sanitizer"] = 3
+# No throttling on non-Darwin platforms.
+lit_config.parallelism_groups['shadow-memory'] = None
 
-# Force sequential execution when running tests on iOS devices.
-if config.host_os == 'Darwin' and config.apple_platform != "osx" and not config.apple_platform.endswith("sim"):
-  lit_config.warning("iOS device test cases being run sequentially")
-  lit_config.parallelism_groups["ios-device"] = 1
-  config.parallelism_group = "ios-device"
+if platform.system() == 'Darwin':
+  ios_device = config.apple_platform != 'osx' and not config.apple_platform.endswith('sim')
+  # Force sequential execution when running tests on iOS devices.
+  if ios_device:
+    lit_config.warning('Forcing sequential execution for iOS device tests')
+    lit_config.parallelism_groups['ios-device'] = 1
+    config.parallelism_group = 'ios-device'
+
+  # 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')
+    lit_config.parallelism_groups['shadow-memory'] = 3
 
 # Multiple substitutions are necessary to support multiple shared objects used
 # at once.
diff --git a/compiler-rt/test/sanitizer_common/Unit/lit.site.cfg.in b/compiler-rt/test/sanitizer_common/Unit/lit.site.cfg.in
--- a/compiler-rt/test/sanitizer_common/Unit/lit.site.cfg.in
+++ b/compiler-rt/test/sanitizer_common/Unit/lit.site.cfg.in
@@ -12,3 +12,6 @@
 config.test_exec_root = os.path.join("@COMPILER_RT_BINARY_DIR@", "lib",
                                      "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
diff --git a/compiler-rt/test/sanitizer_common/lit.common.cfg b/compiler-rt/test/sanitizer_common/lit.common.cfg
--- a/compiler-rt/test/sanitizer_common/lit.common.cfg
+++ b/compiler-rt/test/sanitizer_common/lit.common.cfg
@@ -71,6 +71,4 @@
 if config.host_os not in ['Linux', 'Darwin', 'NetBSD', 'FreeBSD']:
   config.unsupported = True
 
-if config.host_os == 'Darwin':
-  if config.target_arch in ["x86_64", "x86_64h"]:
-    config.parallelism_group = "darwin-64bit-sanitizer"
+config.parallelism_group = 'shadow-memory'
diff --git a/compiler-rt/test/tsan/lit.cfg b/compiler-rt/test/tsan/lit.cfg
--- a/compiler-rt/test/tsan/lit.cfg
+++ b/compiler-rt/test/tsan/lit.cfg
@@ -85,6 +85,4 @@
 if config.android:
   config.unsupported = True
 
-if config.host_os == 'Darwin':
-  if config.target_arch in ["x86_64", "x86_64h"]:
-    config.parallelism_group = "darwin-64bit-sanitizer"
+config.parallelism_group = 'shadow-memory'
diff --git a/compiler-rt/unittests/lit.common.unit.cfg b/compiler-rt/unittests/lit.common.unit.cfg
--- a/compiler-rt/unittests/lit.common.unit.cfg
+++ b/compiler-rt/unittests/lit.common.unit.cfg
@@ -30,10 +30,10 @@
     config.environment['TEMP'] = os.environ['TEMP']
 
 if config.host_os == 'Darwin':
-  # Only run up to 3 64-bit sanitized processes simultaneously on Darwin.
-  # Using more scales badly and hogs the system due to inefficient handling
-  # of large mmap'd regions (terabytes) by the kernel.
-  lit_config.parallelism_groups["darwin-64bit-sanitizer"] = 3
+  # 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.
+  lit_config.parallelism_groups["shadow-memory"] = 3
 
   # 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.
diff --git a/compiler-rt/unittests/lit_unittest_cfg_utils.py b/compiler-rt/unittests/lit_unittest_cfg_utils.py
--- a/compiler-rt/unittests/lit_unittest_cfg_utils.py
+++ b/compiler-rt/unittests/lit_unittest_cfg_utils.py
@@ -1,4 +1,4 @@
-# Put all 64-bit sanitizer tests in the darwin-64bit-sanitizer parallelism
-# group. This will only run three of them concurrently.
+# Put all 64-bit tests in the shadow-memory parallelism group. We throttle those
+# in our common lit config (lit.common.unit.cfg).
 def darwin_sanitizer_parallelism_group_func(test):
-  return "darwin-64bit-sanitizer" if "x86_64" in test.file_path else ""
+  return "shadow-memory" if "x86_64" in test.file_path else None