diff --git a/sphinx/ext/autodoc/mock.py b/sphinx/ext/autodoc/mock.py
index 71d079c88..cc6e4b366 100644
--- a/sphinx/ext/autodoc/mock.py
+++ b/sphinx/ext/autodoc/mock.py
@@ -9,7 +9,7 @@ from types import MethodType, ModuleType
 from typing import Any, Generator, Iterator, List, Optional, Sequence, Tuple, Union
 
 from sphinx.util import logging
-from sphinx.util.inspect import safe_getattr
+from sphinx.util.inspect import isboundmethod, safe_getattr
 
 logger = logging.getLogger(__name__)
 
@@ -129,14 +129,6 @@ class MockFinder(MetaPathFinder):
             sys.modules.pop(modname, None)
 
 
-def isboundmethod(method: MethodType) -> bool:
-    """Check if the method is a bound method."""
-    try:
-        return method.__self__ is not None
-    except AttributeError:
-        return False
-
-
 @contextlib.contextmanager
 def mock(modnames: List[str]) -> Generator[None, None, None]:
     """Insert mock modules during context::
diff --git a/sphinx/util/inspect.py b/sphinx/util/inspect.py
index 5b4e2586e..e226c74dc 100644
--- a/sphinx/util/inspect.py
+++ b/sphinx/util/inspect.py
@@ -13,7 +13,7 @@ from functools import partial, partialmethod
 from importlib import import_module
 from inspect import Parameter, isclass, ismethod, ismethoddescriptor, ismodule  # NOQA
 from io import StringIO
-from types import ModuleType
+from types import MethodType, ModuleType
 from typing import Any, Callable, Dict, Mapping, Optional, Sequence, Tuple, Type, cast
 
 from sphinx.deprecation import RemovedInSphinx50Warning
@@ -303,6 +303,14 @@ def isabstractmethod(obj: Any) -> bool:
     return safe_getattr(obj, '__isabstractmethod__', False) is True
 
 
+def isboundmethod(method: MethodType) -> bool:
+    """Check if the method is a bound method."""
+    try:
+        return method.__self__ is not None
+    except AttributeError:
+        return False
+
+
 def is_cython_function_or_method(obj: Any) -> bool:
     """Check if the object is a function or method in cython."""
     try: