diff --git a/Doc/library/sys.rst b/Doc/library/sys.rst
index 52026f6a2bce38..88b3511a8d3dcd 100644
--- a/Doc/library/sys.rst
+++ b/Doc/library/sys.rst
@@ -90,6 +90,16 @@ always available.
    A string containing the copyright pertaining to the Python interpreter.
 
 
+.. index:: single: __clearcache__
+
+.. function:: clear_caches()
+
+   Clear all caches. Call the ``__clearcache__()`` function for all
+   imported modules if it is defined.
+
+   ... versionadded: 3.8
+
+
 .. function:: _clear_type_cache()
 
    Clear the internal type cache. The type cache is used to speed up attribute
diff --git a/Doc/tutorial/modules.rst b/Doc/tutorial/modules.rst
index accc30649f24ef..3408adc8ed2537 100644
--- a/Doc/tutorial/modules.rst
+++ b/Doc/tutorial/modules.rst
@@ -311,7 +311,7 @@ defines.  It returns a sorted list of strings::
     '_clear_type_cache', '_current_frames', '_debugmallocstats', '_getframe',
     '_home', '_mercurial', '_xoptions', 'abiflags', 'api_version', 'argv',
     'base_exec_prefix', 'base_prefix', 'builtin_module_names', 'byteorder',
-    'call_tracing', 'callstats', 'copyright', 'displayhook',
+    'call_tracing', 'callstats', 'clear_caches', 'copyright', 'displayhook',
     'dont_write_bytecode', 'exc_info', 'excepthook', 'exec_prefix',
     'executable', 'exit', 'flags', 'float_info', 'float_repr_style',
     'getcheckinterval', 'getdefaultencoding', 'getdlopenflags',
diff --git a/Doc/whatsnew/3.8.rst b/Doc/whatsnew/3.8.rst
index f0423c376fcdd4..d29694b8750459 100644
--- a/Doc/whatsnew/3.8.rst
+++ b/Doc/whatsnew/3.8.rst
@@ -346,6 +346,12 @@ and manipulating normal distributions of a random variable.
     >>> temperature_feb.samples(3)        # Generate random samples
     [7.672102882379219, 12.000027119750287, 4.647488369766392]
 
+sys
+---
+
+Added the :func:`~sys.clear_caches` function. It clears all caches by
+calling the ``__clearcache__()`` function for every module if it is defined.
+(Contributed by Serhit Storchaka in :issue:`36485`.)
 
 tarfile
 -------
diff --git a/Lib/_strptime.py b/Lib/_strptime.py
index f4f3c0b80c1d05..14a0e4f62fde56 100644
--- a/Lib/_strptime.py
+++ b/Lib/_strptime.py
@@ -268,6 +268,7 @@ def compile(self, format):
 _TimeRE_cache = TimeRE()
 _CACHE_MAX_SIZE = 5 # Max number of regexes stored in _regex_cache
 _regex_cache = {}
+__clearcache__ = _regex_cache.clear
 
 def _calc_julian_from_U_or_W(year, week_of_year, day_of_week, week_starts_Mon):
     """Calculate the Julian day based on the year, week of the year, and day of
diff --git a/Lib/ctypes/__init__.py b/Lib/ctypes/__init__.py
index 4107db3e3972d7..19feaa4e166aa9 100644
--- a/Lib/ctypes/__init__.py
+++ b/Lib/ctypes/__init__.py
@@ -267,6 +267,9 @@ def _reset_cache():
     POINTER(c_char).from_param = c_char_p.from_param
     _pointer_type_cache[None] = c_void_p
 
+
+__clearcache__ = _reset_cache
+
 def create_unicode_buffer(init, size=None):
     """create_unicode_buffer(aString) -> character array
     create_unicode_buffer(anInteger) -> character array
diff --git a/Lib/distutils/dir_util.py b/Lib/distutils/dir_util.py
index d5cd8e3e24f46a..b8b8a282fb47c6 100644
--- a/Lib/distutils/dir_util.py
+++ b/Lib/distutils/dir_util.py
@@ -10,6 +10,7 @@
 # cache for by mkpath() -- in addition to cheapening redundant calls,
 # eliminates redundant "creating /foo/bar/baz" messages in dry-run mode
 _path_created = {}
+__clearcache__ = _path_created.clear
 
 # I don't use os.makedirs because a) it's new to Python 1.5.2, and
 # b) it blows up if the directory already exists (I want to silently
diff --git a/Lib/doctest.py b/Lib/doctest.py
index 79d91a040c2eee..3564e1ab57b1bb 100644
--- a/Lib/doctest.py
+++ b/Lib/doctest.py
@@ -1853,6 +1853,10 @@ def report_failure(self, out, test, example, got):
 # class, updated by testmod.
 master = None
 
+def __clearcache__():
+    global master
+    master = None
+
 def testmod(m=None, name=None, globs=None, verbose=None,
             report=True, optionflags=0, extraglobs=None,
             raise_on_error=False, exclude_empty=False):
diff --git a/Lib/filecmp.py b/Lib/filecmp.py
index e5ad8397e4c539..b32c7773fec212 100644
--- a/Lib/filecmp.py
+++ b/Lib/filecmp.py
@@ -26,6 +26,8 @@ def clear_cache():
     """Clear the filecmp cache."""
     _cache.clear()
 
+__clearcache__ = clear_cache
+
 def cmp(f1, f2, shallow=True):
     """Compare two files.
 
diff --git a/Lib/linecache.py b/Lib/linecache.py
index 3afcce1f0a1456..291c4708b2cf84 100644
--- a/Lib/linecache.py
+++ b/Lib/linecache.py
@@ -33,6 +33,7 @@ def clearcache():
     global cache
     cache = {}
 
+__clearcache__ = clearcache
 
 def getlines(filename, module_globals=None):
     """Get the lines for a Python source file from the cache.
diff --git a/Lib/mimetypes.py b/Lib/mimetypes.py
index 8861b75362dbd7..04814e29491841 100644
--- a/Lib/mimetypes.py
+++ b/Lib/mimetypes.py
@@ -548,6 +548,7 @@ def _default_mime_types():
         }
 
 
+__clearcache__ = _default_mime_types
 _default_mime_types()
 
 
diff --git a/Lib/re.py b/Lib/re.py
index 68d62dc2a93b05..b395a5cc9b13df 100644
--- a/Lib/re.py
+++ b/Lib/re.py
@@ -238,6 +238,8 @@ def purge():
     _cache.clear()
     _compile_repl.cache_clear()
 
+__clearcache__ = purge
+
 def template(pattern, flags=0):
     "Compile a template pattern, returning a Pattern object"
     return _compile(pattern, flags|T)
diff --git a/Lib/struct.py b/Lib/struct.py
index d6bba588636498..998f16a042d7a2 100644
--- a/Lib/struct.py
+++ b/Lib/struct.py
@@ -11,5 +11,4 @@
     ]
 
 from _struct import *
-from _struct import _clearcache
 from _struct import __doc__
diff --git a/Lib/test/libregrtest/refleak.py b/Lib/test/libregrtest/refleak.py
index 6724488fcfb088..3a8ce9595b31ef 100644
--- a/Lib/test/libregrtest/refleak.py
+++ b/Lib/test/libregrtest/refleak.py
@@ -136,7 +136,8 @@ def dash_R_cleanup(fs, ps, pic, zdc, abcs):
         zipimport._zip_directory_cache.update(zdc)
 
     # clear type cache
-    sys._clear_type_cache()
+    if hasattr(sys, '_clear_type_cache'):
+        sys._clear_type_cache()
 
     # Clear ABC registries, restoring previously saved ABC registries.
     abs_classes = [getattr(collections.abc, a) for a in collections.abc.__all__]
@@ -160,98 +161,13 @@ def dash_R_cleanup(fs, ps, pic, zdc, abcs):
 def clear_caches():
     import gc
 
-    # Clear the warnings registry, so they can be displayed again
-    for mod in sys.modules.values():
-        if hasattr(mod, '__warningregistry__'):
-            del mod.__warningregistry__
-
     # Flush standard output, so that buffered data is sent to the OS and
     # associated Python objects are reclaimed.
     for stream in (sys.stdout, sys.stderr, sys.__stdout__, sys.__stderr__):
         if stream is not None:
             stream.flush()
 
-    # Clear assorted module caches.
-    # Don't worry about resetting the cache if the module is not loaded
-    try:
-        distutils_dir_util = sys.modules['distutils.dir_util']
-    except KeyError:
-        pass
-    else:
-        distutils_dir_util._path_created.clear()
-    re.purge()
-
-    try:
-        _strptime = sys.modules['_strptime']
-    except KeyError:
-        pass
-    else:
-        _strptime._regex_cache.clear()
-
-    try:
-        urllib_parse = sys.modules['urllib.parse']
-    except KeyError:
-        pass
-    else:
-        urllib_parse.clear_cache()
-
-    try:
-        urllib_request = sys.modules['urllib.request']
-    except KeyError:
-        pass
-    else:
-        urllib_request.urlcleanup()
-
-    try:
-        linecache = sys.modules['linecache']
-    except KeyError:
-        pass
-    else:
-        linecache.clearcache()
-
-    try:
-        mimetypes = sys.modules['mimetypes']
-    except KeyError:
-        pass
-    else:
-        mimetypes._default_mime_types()
-
-    try:
-        filecmp = sys.modules['filecmp']
-    except KeyError:
-        pass
-    else:
-        filecmp._cache.clear()
-
-    try:
-        struct = sys.modules['struct']
-    except KeyError:
-        pass
-    else:
-        struct._clearcache()
-
-    try:
-        doctest = sys.modules['doctest']
-    except KeyError:
-        pass
-    else:
-        doctest.master = None
-
-    try:
-        ctypes = sys.modules['ctypes']
-    except KeyError:
-        pass
-    else:
-        ctypes._reset_cache()
-
-    try:
-        typing = sys.modules['typing']
-    except KeyError:
-        pass
-    else:
-        for f in typing._cleanups:
-            f()
-
+    sys.clear_caches()
     gc.collect()
 
 
diff --git a/Lib/test/test_sys.py b/Lib/test/test_sys.py
index 4bd54af3629c88..5dc6d3398272b6 100644
--- a/Lib/test/test_sys.py
+++ b/Lib/test/test_sys.py
@@ -15,6 +15,8 @@
 # strings to intern in test_intern()
 numruns = 0
 
+cache = []
+__clearcache__ = cache.clear
 
 class SysModuleTest(unittest.TestCase):
 
@@ -556,6 +558,11 @@ def test_sys_getwindowsversion_no_instantiation(self):
         test.support.get_attribute(sys, "getwindowsversion")
         self.assert_raise_on_new_sys_type(sys.getwindowsversion())
 
+    def test_clear_caches(self):
+        cache.append(True)
+        sys.clear_caches()
+        self.assertEqual(cache, [])
+
     @test.support.cpython_only
     def test_clear_type_cache(self):
         sys._clear_type_cache()
diff --git a/Lib/test/test_typing.py b/Lib/test/test_typing.py
index 0d66ebbd18456e..ae943552066a0c 100644
--- a/Lib/test/test_typing.py
+++ b/Lib/test/test_typing.py
@@ -45,8 +45,7 @@ def assertNotIsSubclass(self, cls, class_or_tuple, msg=None):
             raise self.failureException(message)
 
     def clear_caches(self):
-        for f in typing._cleanups:
-            f()
+        typing.__clearcache__()
 
 
 class Employee:
diff --git a/Lib/typing.py b/Lib/typing.py
index 530d4633fe4c22..78f663eb5c7a29 100644
--- a/Lib/typing.py
+++ b/Lib/typing.py
@@ -233,6 +233,10 @@ def _remove_dups_flatten(parameters):
 
 _cleanups = []
 
+def __clearcache__():
+    for f in _cleanups:
+        f()
+
 
 def _tp_cache(func):
     """Internal wrapper caching __getitem__ of generic types with a fallback to
diff --git a/Lib/urllib/parse.py b/Lib/urllib/parse.py
index 8b6c9b10609152..adab39aca47e80 100644
--- a/Lib/urllib/parse.py
+++ b/Lib/urllib/parse.py
@@ -86,6 +86,7 @@ def clear_cache():
     _parse_cache.clear()
     _safe_quoters.clear()
 
+__clearcache__ = clear_cache
 
 # Helpers for bytes handling
 # For 3.2, we deliberately require applications that
diff --git a/Lib/urllib/request.py b/Lib/urllib/request.py
index df2ff06f0fc9a2..a85776003b7535 100644
--- a/Lib/urllib/request.py
+++ b/Lib/urllib/request.py
@@ -302,6 +302,8 @@ def urlcleanup():
     if _opener:
         _opener = None
 
+__clearcache__ = urlcleanup
+
 # copied from cookielib.py
 _cut_port_re = re.compile(r":\d+$", re.ASCII)
 def request_host(request):
diff --git a/Lib/warnings.py b/Lib/warnings.py
index 00f740ca3a95ba..981dd1a7bbd104 100644
--- a/Lib/warnings.py
+++ b/Lib/warnings.py
@@ -538,6 +538,13 @@ def _filters_mutated():
     _warnings_defaults = False
 
 
+def __clearcache__():
+    # Clear the warnings registry, so they can be displayed again
+    for mod in list(sys.modules.values()):
+        if hasattr(mod, '__warningregistry__'):
+            del mod.__warningregistry__
+
+
 # Module initialization
 _processoptions(sys.warnoptions)
 if not _warnings_defaults:
diff --git a/Lib/xml/etree/ElementPath.py b/Lib/xml/etree/ElementPath.py
index ef32917b14d41e..7eb975707f11d5 100644
--- a/Lib/xml/etree/ElementPath.py
+++ b/Lib/xml/etree/ElementPath.py
@@ -251,6 +251,7 @@ def select(context, result):
     }
 
 _cache = {}
+__clearcache__ = _cache.clear
 
 class _SelectorContext:
     parent_map = None
diff --git a/Misc/NEWS.d/next/Library/2019-03-30-14-01-43.bpo-36485.OM96Zf.rst b/Misc/NEWS.d/next/Library/2019-03-30-14-01-43.bpo-36485.OM96Zf.rst
new file mode 100644
index 00000000000000..99a0c4526f8823
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2019-03-30-14-01-43.bpo-36485.OM96Zf.rst
@@ -0,0 +1 @@
+Added the :func:`sys.clear_caches` function.
diff --git a/Modules/_struct.c b/Modules/_struct.c
index 90839b2ead7508..5e88151a051dd9 100644
--- a/Modules/_struct.c
+++ b/Modules/_struct.c
@@ -2112,14 +2112,14 @@ cache_struct_converter(PyObject *fmt, PyStructObject **ptr)
 }
 
 /*[clinic input]
-_clearcache
+__clearcache__
 
 Clear the internal cache.
 [clinic start generated code]*/
 
 static PyObject *
-_clearcache_impl(PyObject *module)
-/*[clinic end generated code: output=ce4fb8a7bf7cb523 input=463eaae04bab3211]*/
+__clearcache___impl(PyObject *module)
+/*[clinic end generated code: output=7d1757711e960187 input=d8c1789f69c336ae]*/
 {
     Py_CLEAR(cache);
     Py_RETURN_NONE;
@@ -2264,7 +2264,7 @@ iter_unpack_impl(PyObject *module, PyStructObject *s_object,
 }
 
 static struct PyMethodDef module_functions[] = {
-    _CLEARCACHE_METHODDEF
+    __CLEARCACHE___METHODDEF
     CALCSIZE_METHODDEF
     ITER_UNPACK_METHODDEF
     {"pack",            (PyCFunction)(void(*)(void))pack, METH_FASTCALL,   pack_doc},
diff --git a/Modules/clinic/_struct.c.h b/Modules/clinic/_struct.c.h
index 908c44266c4ec6..c438627bef21c6 100644
--- a/Modules/clinic/_struct.c.h
+++ b/Modules/clinic/_struct.c.h
@@ -167,22 +167,22 @@ PyDoc_STRVAR(Struct_iter_unpack__doc__,
 #define STRUCT_ITER_UNPACK_METHODDEF    \
     {"iter_unpack", (PyCFunction)Struct_iter_unpack, METH_O, Struct_iter_unpack__doc__},
 
-PyDoc_STRVAR(_clearcache__doc__,
-"_clearcache($module, /)\n"
+PyDoc_STRVAR(__clearcache____doc__,
+"__clearcache__($module, /)\n"
 "--\n"
 "\n"
 "Clear the internal cache.");
 
-#define _CLEARCACHE_METHODDEF    \
-    {"_clearcache", (PyCFunction)_clearcache, METH_NOARGS, _clearcache__doc__},
+#define __CLEARCACHE___METHODDEF    \
+    {"__clearcache__", (PyCFunction)__clearcache__, METH_NOARGS, __clearcache____doc__},
 
 static PyObject *
-_clearcache_impl(PyObject *module);
+__clearcache___impl(PyObject *module);
 
 static PyObject *
-_clearcache(PyObject *module, PyObject *Py_UNUSED(ignored))
+__clearcache__(PyObject *module, PyObject *Py_UNUSED(ignored))
 {
-    return _clearcache_impl(module);
+    return __clearcache___impl(module);
 }
 
 PyDoc_STRVAR(calcsize__doc__,
@@ -386,4 +386,4 @@ iter_unpack(PyObject *module, PyObject *const *args, Py_ssize_t nargs)
 
     return return_value;
 }
-/*[clinic end generated code: output=b642e1002d25ebdd input=a9049054013a1b77]*/
+/*[clinic end generated code: output=c92e2f149a1703cb input=a9049054013a1b77]*/
diff --git a/Python/clinic/sysmodule.c.h b/Python/clinic/sysmodule.c.h
index c70b721983c1c4..b8a938e649dd40 100644
--- a/Python/clinic/sysmodule.c.h
+++ b/Python/clinic/sysmodule.c.h
@@ -971,6 +971,26 @@ sys__debugmallocstats(PyObject *module, PyObject *Py_UNUSED(ignored))
     return sys__debugmallocstats_impl(module);
 }
 
+PyDoc_STRVAR(sys_clear_caches__doc__,
+"clear_caches($module, /)\n"
+"--\n"
+"\n"
+"Clear all caches.\n"
+"\n"
+"Call the __clearcache__() function in every imported module.");
+
+#define SYS_CLEAR_CACHES_METHODDEF    \
+    {"clear_caches", (PyCFunction)sys_clear_caches, METH_NOARGS, sys_clear_caches__doc__},
+
+static PyObject *
+sys_clear_caches_impl(PyObject *module);
+
+static PyObject *
+sys_clear_caches(PyObject *module, PyObject *Py_UNUSED(ignored))
+{
+    return sys_clear_caches_impl(module);
+}
+
 PyDoc_STRVAR(sys__clear_type_cache__doc__,
 "_clear_type_cache($module, /)\n"
 "--\n"
@@ -1060,4 +1080,4 @@ sys_getandroidapilevel(PyObject *module, PyObject *Py_UNUSED(ignored))
 #ifndef SYS_GETANDROIDAPILEVEL_METHODDEF
     #define SYS_GETANDROIDAPILEVEL_METHODDEF
 #endif /* !defined(SYS_GETANDROIDAPILEVEL_METHODDEF) */
-/*[clinic end generated code: output=3ba4c194d00f1866 input=a9049054013a1b77]*/
+/*[clinic end generated code: output=3fc46ed6688d455c input=a9049054013a1b77]*/
diff --git a/Python/sysmodule.c b/Python/sysmodule.c
index 3de94e8468bee1..5882d411f39a14 100644
--- a/Python/sysmodule.c
+++ b/Python/sysmodule.c
@@ -1596,6 +1596,41 @@ extern PyObject *_Py_GetDXProfile(PyObject *,  PyObject *);
 #endif
 
 
+/*[clinic input]
+sys.clear_caches
+
+Clear all caches.
+
+Call the __clearcache__() function in every imported module.
+[clinic start generated code]*/
+
+static PyObject *
+sys_clear_caches_impl(PyObject *module)
+/*[clinic end generated code: output=7bbac9db7bbef6c3 input=9e739bbc710495ff]*/
+{
+    _Py_IDENTIFIER(__clearcache__);
+    PyObject *modules = PyMapping_Values(PyImport_GetModuleDict());
+    for (Py_ssize_t i = PyList_GET_SIZE(modules); i-- > 0;) {
+        PyObject *mod, *func, *res;
+        mod = PyList_GET_ITEM(modules, i);
+        if (_PyObject_LookupAttrId(mod, &PyId___clearcache__, &func) < 0) {
+            Py_DECREF(modules);
+            return NULL;
+        }
+        if (func) {
+            res = _PyObject_CallNoArg(func);
+            Py_DECREF(func);
+            if (res == NULL) {
+                Py_DECREF(modules);
+                return NULL;
+            }
+            Py_DECREF(res);
+        }
+    }
+    Py_DECREF(modules);
+    Py_RETURN_NONE;
+}
+
 /*[clinic input]
 sys._clear_type_cache
 
@@ -1644,6 +1679,7 @@ static PyMethodDef sys_methods[] = {
     {"breakpointhook",  (PyCFunction)(void(*)(void))sys_breakpointhook,
      METH_FASTCALL | METH_KEYWORDS, breakpointhook_doc},
     SYS_CALLSTATS_METHODDEF
+    SYS_CLEAR_CACHES_METHODDEF
     SYS__CLEAR_TYPE_CACHE_METHODDEF
     SYS__CURRENT_FRAMES_METHODDEF
     SYS_DISPLAYHOOK_METHODDEF