diff --git a/pydoctor/astbuilder.py b/pydoctor/astbuilder.py
index bb60cc6..eafdadc 100644
--- a/pydoctor/astbuilder.py
+++ b/pydoctor/astbuilder.py
@@ -322,9 +322,51 @@ class ModuleVistor(ast.NodeVisitor):
                 if not self._handleOldSchoolDecoration(target, expr):
                     self._handleAssignmentInClass(target, annotation, expr, lineno)
         elif isinstance(targetNode, ast.Attribute):
-            value = targetNode.value
-            if isinstance(value, ast.Name) and value.id == 'self':
-                self._handleInstanceVar(targetNode.attr, annotation, lineno)
+            # Handle __doc__ assignments to update docstrings after-the-fact
+            if targetNode.attr == '__doc__':
+                self._handleDocstringAssignment(targetNode.value, expr, lineno)
+            else:
+                value = targetNode.value
+                if isinstance(value, ast.Name) and value.id == 'self':
+                    self._handleInstanceVar(targetNode.attr, annotation, lineno)
+
+    def _handleDocstringAssignment(self, targetNode, valueNode, lineno):
+        """Handle assignments of the form object.__doc__ = "docstring"."""
+        # Only handle string literals for docstring values
+        if not isinstance(valueNode, ast.Str):
+            self.builder.warning(
+                ":{}:".format(lineno),
+                "Ignoring value assigned to __doc__: not a string"
+            )
+            return
+
+        # Resolve what the target refers to (e.g., 'fun' in 'fun.__doc__')
+        target_fullname = node2fullname(targetNode, self.builder.current)
+        if target_fullname is None:
+            self.builder.warning(
+                ":{}:".format(lineno),
+                "Unable to figure out target for __doc__ assignment"
+            )
+            return
+
+        # Find the object in our system
+        target_obj = self.system.objForFullName(target_fullname)
+        if target_obj is None:
+            target_source = astor.to_source(targetNode).strip()
+            self.builder.warning(
+                ":{}:".format(lineno),
+                "Unable to figure out target for __doc__ assignment: computed full name not found: {}".format(target_source)
+            )
+            return
+
+        # Update the docstring if it's a function, class, or module
+        if isinstance(target_obj, (model.Function, model.Class, model.Module)):
+            target_obj.docstring = valueNode.s
+        else:
+            self.builder.warning(
+                ":{}:".format(lineno),
+                "Unable to figure out value for __doc__ assignment: maybe too complex"
+            )
 
     def visit_Assign(self, node):
         lineno = node.lineno