diff --git a/CHANGES b/CHANGES
index 84f1798c386..181b33ec3d8 100644
--- a/CHANGES
+++ b/CHANGES
@@ -41,6 +41,7 @@ Bugs fixed
   typing.Generic
 * #8157: autodoc: TypeError is raised when annotation has invalid __args__
 * #7964: autodoc: Tuple in default value is wrongly rendered
+* #7786: autodoc: can't detect overloaded methods defined in other file
 * #8192: napoleon: description is disappeared when it contains inline literals
 * #8142: napoleon: Potential of regex denial of service in google style docs
 * #8169: LaTeX: pxjahyper loaded even when latex_engine is not platex
diff --git a/sphinx/ext/autodoc/__init__.py b/sphinx/ext/autodoc/__init__.py
index 6eff2710222..5b46339a121 100644
--- a/sphinx/ext/autodoc/__init__.py
+++ b/sphinx/ext/autodoc/__init__.py
@@ -1471,22 +1471,14 @@ def format_signature(self, **kwargs: Any) -> str:
             return ''
 
         sig = super().format_signature()
-
-        overloaded = False
-        qualname = None
-        # TODO: recreate analyzer for the module of class (To be clear, owner of the method)
-        if self._signature_class and self._signature_method_name and self.analyzer:
-            qualname = '.'.join([self._signature_class.__qualname__,
-                                 self._signature_method_name])
-            if qualname in self.analyzer.overloads:
-                overloaded = True
-
         sigs = []
-        if overloaded:
+
+        overloads = self.get_overloaded_signatures()
+        if overloads:
             # Use signatures for overloaded methods instead of the implementation method.
             method = safe_getattr(self._signature_class, self._signature_method_name, None)
             __globals__ = safe_getattr(method, '__globals__', {})
-            for overload in self.analyzer.overloads.get(qualname):
+            for overload in overloads:
                 overload = evaluate_signature(overload, __globals__,
                                               self.env.config.autodoc_type_aliases)
 
@@ -1500,6 +1492,16 @@ def format_signature(self, **kwargs: Any) -> str:
 
         return "\n".join(sigs)
 
+    def get_overloaded_signatures(self) -> List[Signature]:
+        if self._signature_class and self._signature_method_name:
+            for cls in self._signature_class.__mro__:
+                analyzer = ModuleAnalyzer.for_module(cls.__module__)
+                qualname = '.'.join([cls.__qualname__, self._signature_method_name])
+                if qualname in analyzer.overloads:
+                    return analyzer.overloads.get(qualname)
+
+        return []
+
     def add_directive_header(self, sig: str) -> None:
         sourcename = self.get_sourcename()
 
diff --git a/tests/roots/test-ext-autodoc/target/overload2.py b/tests/roots/test-ext-autodoc/target/overload2.py
new file mode 100644
index 00000000000..e901f791b2f
--- /dev/null
+++ b/tests/roots/test-ext-autodoc/target/overload2.py
@@ -0,0 +1,5 @@
+from target.overload import Bar
+
+
+class Baz(Bar):
+    pass
diff --git a/tests/test_ext_autodoc.py b/tests/test_ext_autodoc.py
index 7fff09bb6b6..9cb54de5b06 100644
--- a/tests/test_ext_autodoc.py
+++ b/tests/test_ext_autodoc.py
@@ -2002,6 +2002,22 @@ def test_overload(app):
     ]
 
 
+@pytest.mark.sphinx('html', testroot='ext-autodoc')
+def test_overload2(app):
+    options = {"members": None}
+    actual = do_autodoc(app, 'module', 'target.overload2', options)
+    assert list(actual) == [
+        '',
+        '.. py:module:: target.overload2',
+        '',
+        '',
+        '.. py:class:: Baz(x: int, y: int)',
+        '              Baz(x: str, y: str)',
+        '   :module: target.overload2',
+        '',
+    ]
+
+
 @pytest.mark.sphinx('html', testroot='ext-autodoc')
 def test_pymodule_for_ModuleLevelDocumenter(app):
     app.env.ref_context['py:module'] = 'target.classes'