As mentioned by @saimn in #7162 (comment) , this feature is finally implemented upstream by Sphinx. When Sphinx minversion >=1.7, InheritDocstrings can be deprecated, to be removed in a future release afterwards.

sphinx-doc/sphinx#4126
sphinx-doc/sphinx#4129
https://github.com/sphinx-doc/sphinx/blob/0fb832baa54a791bbca0be620bad47b6c69b680c/CHANGES#L1326-L1327 -- In case of missing docstring try to retrieve doc from base classes (ref: sphinx-doc/sphinx#3140)