diff --git a/doc/usage/extensions/autosummary.rst b/doc/usage/extensions/autosummary.rst
index 60e66edbd13..d50abd89e92 100644
--- a/doc/usage/extensions/autosummary.rst
+++ b/doc/usage/extensions/autosummary.rst
@@ -195,6 +195,15 @@ also use these config values:
 
    .. versionadded:: 2.1
 
+.. confval:: autosummary_filename_map
+
+   A dict mapping object names to filenames. This is necessary to avoid
+   filename conflicts where multiple objects have names that are
+   indistinguishable when case is ignored, on file systems where filenames
+   are case-insensitive.
+
+   .. versionadded:: 3.2
+
 
 Customizing templates
 ---------------------
diff --git a/sphinx/ext/autosummary/__init__.py b/sphinx/ext/autosummary/__init__.py
index 0984377c565..350604387b0 100644
--- a/sphinx/ext/autosummary/__init__.py
+++ b/sphinx/ext/autosummary/__init__.py
@@ -252,7 +252,9 @@ def run(self) -> List[Node]:
             tree_prefix = self.options['toctree'].strip()
             docnames = []
             excluded = Matcher(self.config.exclude_patterns)
+            filename_map = self.config.autosummary_filename_map
             for name, sig, summary, real_name in items:
+                real_name = filename_map.get(real_name, real_name)
                 docname = posixpath.join(tree_prefix, real_name)
                 docname = posixpath.normpath(posixpath.join(dirname, docname))
                 if docname not in self.env.found_docs:
@@ -785,6 +787,7 @@ def setup(app: Sphinx) -> Dict[str, Any]:
     app.add_role('autolink', AutoLink())
     app.connect('builder-inited', process_generate_options)
     app.add_config_value('autosummary_context', {}, True)
+    app.add_config_value('autosummary_filename_map', {}, 'html')
     app.add_config_value('autosummary_generate', [], True, [bool])
     app.add_config_value('autosummary_generate_overwrite', True, False)
     app.add_config_value('autosummary_mock_imports',
diff --git a/sphinx/ext/autosummary/generate.py b/sphinx/ext/autosummary/generate.py
index d908e208822..c1b50de577a 100644
--- a/sphinx/ext/autosummary/generate.py
+++ b/sphinx/ext/autosummary/generate.py
@@ -74,6 +74,7 @@ def __init__(self, translator: NullTranslations) -> None:
         self.warningiserror = False
 
         self.config.add('autosummary_context', {}, True, None)
+        self.config.add('autosummary_filename_map', {}, True, None)
         self.config.init_values()
 
     def emit_firstresult(self, *args: Any) -> None:
@@ -393,6 +394,11 @@ def generate_autosummary_docs(sources: List[str], output_dir: str = None,
     # keep track of new files
     new_files = []
 
+    if app:
+        filename_map = app.config.autosummary_filename_map
+    else:
+        filename_map = {}
+
     # write
     for entry in sorted(set(items), key=str):
         if entry.path is None:
@@ -418,7 +424,7 @@ def generate_autosummary_docs(sources: List[str], output_dir: str = None,
                                                imported_members, app, entry.recursive, context,
                                                modname, qualname)
 
-        filename = os.path.join(path, name + suffix)
+        filename = os.path.join(path, filename_map.get(name, name) + suffix)
         if os.path.isfile(filename):
             with open(filename, encoding=encoding) as f:
                 old_content = f.read()
diff --git a/tests/roots/test-ext-autosummary-filename-map/autosummary_dummy_module.py b/tests/roots/test-ext-autosummary-filename-map/autosummary_dummy_module.py
new file mode 100644
index 00000000000..1f57eeb256c
--- /dev/null
+++ b/tests/roots/test-ext-autosummary-filename-map/autosummary_dummy_module.py
@@ -0,0 +1,21 @@
+from os import path  # NOQA
+from typing import Union
+
+
+class Foo:
+    class Bar:
+        pass
+
+    def __init__(self):
+        pass
+
+    def bar(self):
+        pass
+
+    @property
+    def baz(self):
+        pass
+
+
+def bar(x: Union[int, str], y: int = 1) -> None:
+    pass
diff --git a/tests/roots/test-ext-autosummary-filename-map/conf.py b/tests/roots/test-ext-autosummary-filename-map/conf.py
new file mode 100644
index 00000000000..17e2fa44565
--- /dev/null
+++ b/tests/roots/test-ext-autosummary-filename-map/conf.py
@@ -0,0 +1,11 @@
+import os
+import sys
+
+sys.path.insert(0, os.path.abspath('.'))
+
+extensions = ['sphinx.ext.autosummary']
+autosummary_generate = True
+autosummary_filename_map = {
+    "autosummary_dummy_module": "module_mangled",
+    "autosummary_dummy_module.bar": "bar"
+}
diff --git a/tests/roots/test-ext-autosummary-filename-map/index.rst b/tests/roots/test-ext-autosummary-filename-map/index.rst
new file mode 100644
index 00000000000..57d902b6aba
--- /dev/null
+++ b/tests/roots/test-ext-autosummary-filename-map/index.rst
@@ -0,0 +1,9 @@
+
+.. autosummary::
+   :toctree: generated
+   :caption: An autosummary
+
+   autosummary_dummy_module
+   autosummary_dummy_module.Foo
+   autosummary_dummy_module.Foo.bar
+   autosummary_dummy_module.bar
diff --git a/tests/test_ext_autosummary.py b/tests/test_ext_autosummary.py
index ede19f632d2..567a8caeaa5 100644
--- a/tests/test_ext_autosummary.py
+++ b/tests/test_ext_autosummary.py
@@ -394,6 +394,20 @@ def test_autosummary_recursive(app, status, warning):
     assert 'package.package.module' in content
 
 
+@pytest.mark.sphinx('dummy', testroot='ext-autosummary-filename-map')
+def test_autosummary_filename_map(app, status, warning):
+    app.build()
+
+    assert (app.srcdir / 'generated' / 'module_mangled.rst').exists()
+    assert not (app.srcdir / 'generated' / 'autosummary_dummy_module.rst').exists()
+    assert (app.srcdir / 'generated' / 'bar.rst').exists()
+    assert not (app.srcdir / 'generated' / 'autosummary_dummy_module.bar.rst').exists()
+    assert (app.srcdir / 'generated' / 'autosummary_dummy_module.Foo.rst').exists()
+
+    html_warnings = app._warning.getvalue()
+    assert html_warnings == ''
+
+
 @pytest.mark.sphinx('latex', **default_kw)
 def test_autosummary_latex_table_colspec(app, status, warning):
     app.builder.build_all()