python
diff --git a/Lib/test/libregrtest/main.py b/Lib/test/libregrtest/main.py
@@ -11,8 +11,8 @@
 import unittest
 from test.libregrtest.cmdline import _parse_args
 from test.libregrtest.runtest import (
-    findtests, runtest, get_abs_module, is_failed,
-    STDTESTS, NOTTESTS, PROGRESS_MIN_TIME,
+    findtests, split_test_packages, runtest, get_abs_module, is_failed,
+    PROGRESS_MIN_TIME,
     Passed, Failed, EnvChanged, Skipped, ResourceDenied, Interrupted,
     ChildError, DidNotRun)
 from test.libregrtest.setup import setup_tests
@@ -246,26 +246,23 @@ def find_tests(self, tests):
             # add default PGO tests if no tests are specified
             setup_pgo_tests(self.ns)
 
-        stdtests = STDTESTS[:]
-        nottests = NOTTESTS.copy()
+        exclude = set()
         if self.ns.exclude:
             for arg in self.ns.args:
-                if arg in stdtests:
-                    stdtests.remove(arg)
-                nottests.add(arg)
+                exclude.add(arg)
             self.ns.args = []
 
-        # if testdir is set, then we are not running the python tests suite, so
-        # don't add default tests to be executed or skipped (pass empty values)
-        if self.ns.testdir:
-            alltests = findtests(self.ns.testdir, list(), set())
-        else:
-            alltests = findtests(self.ns.testdir, stdtests, nottests)
+        alltests = findtests(testdir=self.ns.testdir, exclude=exclude)
 
         if not self.ns.fromfile:
-            self.selected = self.tests or self.ns.args or alltests
+            self.selected = self.tests or self.ns.args
+            if self.selected:
+                self.selected = split_test_packages(self.selected)
+            else:
+                self.selected = alltests
         else:
             self.selected = self.tests
+
         if self.ns.single:
             self.selected = self.selected[:1]
             try:

diff --git a/Lib/test/libregrtest/runtest.py b/Lib/test/libregrtest/runtest.py
@@ -125,24 +125,6 @@ def __str__(self) -> str:
 # the test is running in background
 PROGRESS_MIN_TIME = 30.0   # seconds
 
-# small set of tests to determine if we have a basically functioning interpreter
-# (i.e. if any of these fail, then anything else is likely to follow)
-STDTESTS = [
-    'test_grammar',
-    'test_opcodes',
-    'test_dict',
-    'test_builtin',
-    'test_exceptions',
-    'test_types',
-    'test_unittest',
-    'test_doctest',
-    'test_doctest2',
-    'test_support'
-]
-
-# set of tests that we don't want to be executed when using regrtest
-NOTTESTS = set()
-
 #If these test directories are encountered recurse into them and treat each
 # test_ .py or dir as a separate test module. This can increase parallelism.
 # Beware this can't generally be done for any directory with sub-tests as the
@@ -166,22 +148,38 @@ def findtestdir(path=None):
     return path or os.path.dirname(os.path.dirname(__file__)) or os.curdir
 
 
-def findtests(testdir=None, stdtests=STDTESTS, nottests=NOTTESTS, *, split_test_dirs=SPLITTESTDIRS, base_mod=""):
+def findtests(*, testdir=None, exclude=(),
+              split_test_dirs=SPLITTESTDIRS, base_mod=""):
     """Return a list of all applicable test modules."""
     testdir = findtestdir(testdir)
-    names = os.listdir(testdir)
     tests = []
-    others = set(stdtests) | nottests
-    for name in names:
+    for name in os.listdir(testdir):
         mod, ext = os.path.splitext(name)
-        if mod[:5] == "test_" and mod not in others:
-            if mod in split_test_dirs:
-                subdir = os.path.join(testdir, mod)
-                mod = f"{base_mod or 'test'}.{mod}"
-                tests.extend(findtests(subdir, [], nottests, split_test_dirs=split_test_dirs, base_mod=mod))
-            elif ext in (".py", ""):
-                tests.append(f"{base_mod}.{mod}" if base_mod else mod)
-    return stdtests + sorted(tests)
+        if (not mod.startswith("test_")) or (mod in exclude):
+            continue
+        if mod in split_test_dirs:
+            subdir = os.path.join(testdir, mod)
+            mod = f"{base_mod or 'test'}.{mod}"
+            tests.extend(findtests(testdir=subdir, exclude=exclude,
+                                   split_test_dirs=split_test_dirs, base_mod=mod))
+        elif ext in (".py", ""):
+            tests.append(f"{base_mod}.{mod}" if base_mod else mod)
+    return sorted(tests)
+
+
+def split_test_packages(tests, *, testdir=None, exclude=(),
+                        split_test_dirs=SPLITTESTDIRS):
+    testdir = findtestdir(testdir)
+    splitted = []
+    for name in tests:
+        if name in split_test_dirs:
+            subdir = os.path.join(testdir, name)
+            splitted.extend(findtests(testdir=subdir, exclude=exclude,
+                                      split_test_dirs=split_test_dirs,
+                                      base_mod=name))
+        else:
+            splitted.append(name)
+    return splitted
 
 
 def get_abs_module(ns: Namespace, test_name: str) -> str: