diff --git a/Lib/test/libregrtest/main.py b/Lib/test/libregrtest/main.py
index f410bfd..fbbfa73 100644
--- a/Lib/test/libregrtest/main.py
+++ b/Lib/test/libregrtest/main.py
@@ -1,19 +1,16 @@
-import faulthandler
 import os
 import platform
 import random
 import re
-import signal
 import sys
 import sysconfig
 import tempfile
 import textwrap
-import unittest
 from test.libregrtest.runtest import (
     findtests, runtest,
     STDTESTS, NOTTESTS, PASSED, FAILED, ENV_CHANGED, SKIPPED, RESOURCE_DENIED)
-from test.libregrtest.refleak import warm_caches
 from test.libregrtest.cmdline import _parse_args
+from test.libregrtest.setup import setup_python
 from test import support
 try:
     import gc
@@ -31,88 +28,6 @@
 TEMPDIR = os.path.abspath(TEMPDIR)
 
 
-def setup_python(ns):
-    # Display the Python traceback on fatal errors (e.g. segfault)
-    faulthandler.enable(all_threads=True)
-
-    # Display the Python traceback on SIGALRM or SIGUSR1 signal
-    signals = []
-    if hasattr(signal, 'SIGALRM'):
-        signals.append(signal.SIGALRM)
-    if hasattr(signal, 'SIGUSR1'):
-        signals.append(signal.SIGUSR1)
-    for signum in signals:
-        faulthandler.register(signum, chain=True)
-
-    replace_stdout()
-    support.record_original_stdout(sys.stdout)
-
-    # Some times __path__ and __file__ are not absolute (e.g. while running from
-    # Lib/) and, if we change the CWD to run the tests in a temporary dir, some
-    # imports might fail.  This affects only the modules imported before os.chdir().
-    # These modules are searched first in sys.path[0] (so '' -- the CWD) and if
-    # they are found in the CWD their __file__ and __path__ will be relative (this
-    # happens before the chdir).  All the modules imported after the chdir, are
-    # not found in the CWD, and since the other paths in sys.path[1:] are absolute
-    # (site.py absolutize them), the __file__ and __path__ will be absolute too.
-    # Therefore it is necessary to absolutize manually the __file__ and __path__ of
-    # the packages to prevent later imports to fail when the CWD is different.
-    for module in sys.modules.values():
-        if hasattr(module, '__path__'):
-            module.__path__ = [os.path.abspath(path)
-                               for path in module.__path__]
-        if hasattr(module, '__file__'):
-            module.__file__ = os.path.abspath(module.__file__)
-
-    # MacOSX (a.k.a. Darwin) has a default stack size that is too small
-    # for deeply recursive regular expressions.  We see this as crashes in
-    # the Python test suite when running test_re.py and test_sre.py.  The
-    # fix is to set the stack limit to 2048.
-    # This approach may also be useful for other Unixy platforms that
-    # suffer from small default stack limits.
-    if sys.platform == 'darwin':
-        try:
-            import resource
-        except ImportError:
-            pass
-        else:
-            soft, hard = resource.getrlimit(resource.RLIMIT_STACK)
-            newsoft = min(hard, max(soft, 1024*2048))
-            resource.setrlimit(resource.RLIMIT_STACK, (newsoft, hard))
-
-    if ns.huntrleaks:
-        unittest.BaseTestSuite._cleanup = False
-
-        # Avoid false positives due to various caches
-        # filling slowly with random data:
-        warm_caches()
-
-    if ns.memlimit is not None:
-        support.set_memlimit(ns.memlimit)
-
-    if ns.threshold is not None:
-        if gc is not None:
-            gc.set_threshold(ns.threshold)
-        else:
-            print('No GC available, ignore --threshold.')
-
-    if ns.nowindows:
-        import msvcrt
-        msvcrt.SetErrorMode(msvcrt.SEM_FAILCRITICALERRORS|
-                            msvcrt.SEM_NOALIGNMENTFAULTEXCEPT|
-                            msvcrt.SEM_NOGPFAULTERRORBOX|
-                            msvcrt.SEM_NOOPENFILEERRORBOX)
-        try:
-            msvcrt.CrtSetReportMode
-        except AttributeError:
-            # release build
-            pass
-        else:
-            for m in [msvcrt.CRT_WARN, msvcrt.CRT_ERROR, msvcrt.CRT_ASSERT]:
-                msvcrt.CrtSetReportMode(m, msvcrt.CRTDBG_MODE_FILE)
-                msvcrt.CrtSetReportFile(m, msvcrt.CRTDBG_FILE_STDERR)
-
-
 class Regrtest:
     """Execute a test suite.
 
@@ -192,8 +107,14 @@
                          self.test_count, len(self.bad), test),
               flush=True)
 
-    def setup_regrtest(self):
-        if self.ns.findleaks:
+    def parse_args(self, kwargs):
+        ns = _parse_args(sys.argv[1:], **kwargs)
+
+        if ns.threshold is not None and gc is None:
+            print('No GC available, ignore --threshold.')
+            ns.threshold = None
+
+        if ns.findleaks:
             if gc is not None:
                 # Uncomment the line below to report garbage that is not
                 # freeable by reference counting alone.  By default only
@@ -202,10 +123,12 @@
                 #gc.set_debug(gc.DEBUG_SAVEALL)
             else:
                 print('No GC available, disabling --findleaks')
-                self.ns.findleaks = False
+                ns.findleaks = False
 
         # Strip .py extensions.
-        removepy(self.ns.args)
+        removepy(ns.args)
+
+        return ns
 
     def find_tests(self, tests):
         self.tests = tests
@@ -434,9 +357,9 @@
             os.system("leaks %d" % os.getpid())
 
     def main(self, tests=None, **kwargs):
-        self.ns = _parse_args(sys.argv[1:], **kwargs)
+        self.ns = self.parse_args(kwargs)
+
         setup_python(self.ns)
-        self.setup_regrtest()
 
         if self.ns.slaveargs is not None:
             from test.libregrtest.runtest_mp import run_tests_slave
@@ -452,24 +375,6 @@
         sys.exit(len(self.bad) > 0 or self.interrupted)
 
 
-def replace_stdout():
-    """Set stdout encoder error handler to backslashreplace (as stderr error
-    handler) to avoid UnicodeEncodeError when printing a traceback"""
-    import atexit
-
-    stdout = sys.stdout
-    sys.stdout = open(stdout.fileno(), 'w',
-        encoding=stdout.encoding,
-        errors="backslashreplace",
-        closefd=False,
-        newline='\n')
-
-    def restore_stdout():
-        sys.stdout.close()
-        sys.stdout = stdout
-    atexit.register(restore_stdout)
-
-
 def removepy(names):
     if not names:
         return
diff --git a/Lib/test/libregrtest/setup.py b/Lib/test/libregrtest/setup.py
new file mode 100644
index 0000000..a7dfa79
--- /dev/null
+++ b/Lib/test/libregrtest/setup.py
@@ -0,0 +1,108 @@
+import atexit
+import faulthandler
+import os
+import signal
+import sys
+import unittest
+from test import support
+try:
+    import gc
+except ImportError:
+    gc = None
+
+from test.libregrtest.refleak import warm_caches
+
+
+def setup_python(ns):
+    # Display the Python traceback on fatal errors (e.g. segfault)
+    faulthandler.enable(all_threads=True)
+
+    # Display the Python traceback on SIGALRM or SIGUSR1 signal
+    signals = []
+    if hasattr(signal, 'SIGALRM'):
+        signals.append(signal.SIGALRM)
+    if hasattr(signal, 'SIGUSR1'):
+        signals.append(signal.SIGUSR1)
+    for signum in signals:
+        faulthandler.register(signum, chain=True)
+
+    replace_stdout()
+    support.record_original_stdout(sys.stdout)
+
+    # Some times __path__ and __file__ are not absolute (e.g. while running from
+    # Lib/) and, if we change the CWD to run the tests in a temporary dir, some
+    # imports might fail.  This affects only the modules imported before os.chdir().
+    # These modules are searched first in sys.path[0] (so '' -- the CWD) and if
+    # they are found in the CWD their __file__ and __path__ will be relative (this
+    # happens before the chdir).  All the modules imported after the chdir, are
+    # not found in the CWD, and since the other paths in sys.path[1:] are absolute
+    # (site.py absolutize them), the __file__ and __path__ will be absolute too.
+    # Therefore it is necessary to absolutize manually the __file__ and __path__ of
+    # the packages to prevent later imports to fail when the CWD is different.
+    for module in sys.modules.values():
+        if hasattr(module, '__path__'):
+            module.__path__ = [os.path.abspath(path)
+                               for path in module.__path__]
+        if hasattr(module, '__file__'):
+            module.__file__ = os.path.abspath(module.__file__)
+
+    # MacOSX (a.k.a. Darwin) has a default stack size that is too small
+    # for deeply recursive regular expressions.  We see this as crashes in
+    # the Python test suite when running test_re.py and test_sre.py.  The
+    # fix is to set the stack limit to 2048.
+    # This approach may also be useful for other Unixy platforms that
+    # suffer from small default stack limits.
+    if sys.platform == 'darwin':
+        try:
+            import resource
+        except ImportError:
+            pass
+        else:
+            soft, hard = resource.getrlimit(resource.RLIMIT_STACK)
+            newsoft = min(hard, max(soft, 1024*2048))
+            resource.setrlimit(resource.RLIMIT_STACK, (newsoft, hard))
+
+    if ns.huntrleaks:
+        unittest.BaseTestSuite._cleanup = False
+
+        # Avoid false positives due to various caches
+        # filling slowly with random data:
+        warm_caches()
+
+    if ns.memlimit is not None:
+        support.set_memlimit(ns.memlimit)
+
+    if ns.threshold is not None:
+        gc.set_threshold(ns.threshold)
+
+    if ns.nowindows:
+        import msvcrt
+        msvcrt.SetErrorMode(msvcrt.SEM_FAILCRITICALERRORS|
+                            msvcrt.SEM_NOALIGNMENTFAULTEXCEPT|
+                            msvcrt.SEM_NOGPFAULTERRORBOX|
+                            msvcrt.SEM_NOOPENFILEERRORBOX)
+        try:
+            msvcrt.CrtSetReportMode
+        except AttributeError:
+            # release build
+            pass
+        else:
+            for m in [msvcrt.CRT_WARN, msvcrt.CRT_ERROR, msvcrt.CRT_ASSERT]:
+                msvcrt.CrtSetReportMode(m, msvcrt.CRTDBG_MODE_FILE)
+                msvcrt.CrtSetReportFile(m, msvcrt.CRTDBG_FILE_STDERR)
+
+
+def replace_stdout():
+    """Set stdout encoder error handler to backslashreplace (as stderr error
+    handler) to avoid UnicodeEncodeError when printing a traceback"""
+    stdout = sys.stdout
+    sys.stdout = open(stdout.fileno(), 'w',
+        encoding=stdout.encoding,
+        errors="backslashreplace",
+        closefd=False,
+        newline='\n')
+
+    def restore_stdout():
+        sys.stdout.close()
+        sys.stdout = stdout
+    atexit.register(restore_stdout)