python
@@ -182,6 +182,12 @@ PyAPI_FUNC(int) _PyConfig_FromDict(PyConfig *config, PyObject *dict);
 PyAPI_FUNC(PyObject*) _Py_Get_Getpath_CodeObject(void);
 PyAPI_FUNC(PyObject*) _Py_GetConfigsAsDict(void);
 
+PyAPI_FUNC(int) _PyConfig_Parse(
+    PyObject *config_dict,
+    // UTF-8 encoded string
+    const char *config_str
+);
+
 #ifdef __cplusplus
 }
 #endif

@@ -0,0 +1,84 @@
+import textwrap
+import unittest
+from test.support import import_helper
+
+_testinternalcapi = import_helper.import_module('_testinternalcapi')
+
+
+class InitConfigTests(unittest.TestCase):
+    def check_parse(self, text, expected):
+        text = textwrap.dedent(text)
+        config = _testinternalcapi.parse_config_text(text)
+        self.assertEqual(config, expected)
+
+    def test_parse(self):
+        self.check_parse('verbose=1', {'verbose': 1})
+
+        # strip spaces
+        self.check_parse(' \tverbose = 1 ', {'verbose': 1})
+
+        # comments
+        self.check_parse('''
+            verbose=1
+            # ignored comment
+            verbose=2 # more #hashtag comment
+        ''', dict(
+            verbose = 2,
+        ))
+        self.check_parse('verbose=1', {'verbose': 1})
+
+        # types
+        self.check_parse('''
+            # int
+            int_max_str_digits = -123
+
+            # uint
+            isolated = 0
+
+            # ulong
+            hash_seed = 555
+
+            # wstr
+            filesystem_encoding = 'with spaces'
+            filesystem_errors = "double quotes"
+            program_name = "key=value"
+
+            # wstr optional
+            pycache_prefix =
+
+            # == wstr list ==
+
+            argv = ['python', '-c', 'pass']
+
+            # accept spaces before/after strings and commas
+            orig_argv = [ 'python' , '-c' , 'accept spaces, and commas' ]
+
+            # empty list
+            xoptions = []
+        ''', dict(
+            int_max_str_digits = -123,
+            isolated = 0,
+            hash_seed = 555,
+            filesystem_encoding = "with spaces",
+            filesystem_errors = "double quotes",
+            program_name = "key=value",
+            pycache_prefix = None,
+            argv = ['python', '-c', 'pass'],
+            orig_argv = ['python', '-c', 'accept spaces, and commas'],
+            xoptions = [],
+        ))
+
+    def check_error(self, text):
+        text = textwrap.dedent(text)
+        with self.assertRaises(ValueError):
+            _testinternalcapi.parse_config_text(text)
+
+    def test_parse_invalid(self):
+        # no value
+        self.check_error('isolated=')
+        # no key
+        self.check_error('= 123')
+
+
+if __name__ == "__main__":
+    unittest.main()
diff --git a/Modules/_testinternalcapi.c b/Modules/_testinternalcapi.c
@@ -341,6 +341,77 @@ test_set_config(PyObject *Py_UNUSED(self), PyObject *dict)
 }
 
 
+static PyObject *
+test_parse_config_text(PyObject *Py_UNUSED(self), PyObject *config_obj)
+{
+    const char *config_utf8 = PyUnicode_AsUTF8(config_obj);
+    if (config_utf8 == NULL) {
+        return NULL;
+    }
+
+    PyObject *config_dict = PyDict_New();
+    if (config_dict == NULL) {
+        return NULL;
+    }
+
+    if (_PyConfig_Parse(config_dict, config_utf8) < 0) {
+        Py_DECREF(config_dict);
+        return NULL;
+    }
+    return config_dict;
+}
+
+
+static PyObject *
+test_set_config_text(PyObject *Py_UNUSED(self), PyObject *config_obj)
+{
+    if (!PyUnicode_Check(config_obj)) {
+        PyErr_Format(PyExc_TypeError, "expected str, got %s",
+                     Py_TYPE(config_obj)->tp_name);
+        return NULL;
+    }
+
+    PyConfig config;
+    PyConfig_InitIsolatedConfig(&config);
+    PyObject *config_dict = NULL;
+
+    // Set config from the dict
+    if (_PyInterpreterState_GetConfigCopy(&config) < 0) {
+        goto error;
+    }
+    config_dict = _PyConfig_AsDict(&config);
+    if (config_dict == NULL) {
+        goto error;
+    }
+
+    // Parse config text
+    const char *config_utf8 = PyUnicode_AsUTF8(config_obj);
+    if (config_utf8 == NULL) {
+        goto error;
+    }
+    if (_PyConfig_Parse(config_dict, config_utf8) < 0) {
+        goto error;
+    }
+
+    // Set config from dict
+    if (_PyConfig_FromDict(&config, config_dict) < 0) {
+        goto error;
+    }
+    if (_PyInterpreterState_SetConfig(&config) < 0) {
+        goto error;
+    }
+
+    PyConfig_Clear(&config);
+    Py_DECREF(config_dict);
+    Py_RETURN_NONE;
+
+error:
+    PyConfig_Clear(&config);
+    Py_DECREF(config_dict);
+    return NULL;
+}
+
+
 static PyObject *
 test_reset_path_config(PyObject *Py_UNUSED(self), PyObject *Py_UNUSED(arg))
 {
@@ -1536,6 +1607,8 @@ static PyMethodDef module_functions[] = {
     {"test_hashtable", test_hashtable, METH_NOARGS},
     {"get_config", test_get_config, METH_NOARGS},
     {"set_config", test_set_config, METH_O},
+    {"parse_config_text", test_parse_config_text, METH_O},
+    {"set_config_text", test_set_config_text, METH_O},
     {"reset_path_config", test_reset_path_config, METH_NOARGS},
     {"test_edit_cost", test_edit_cost, METH_NOARGS},
     {"test_bytes_find", test_bytes_find, METH_NOARGS},