diff --git a/clang/include/clang/Basic/Attr.td b/clang/include/clang/Basic/Attr.td
--- a/clang/include/clang/Basic/Attr.td
+++ b/clang/include/clang/Basic/Attr.td
@@ -1084,7 +1084,7 @@
   let Spellings = [GCC<"cleanup">];
   let Args = [DeclArgument<Function, "FunctionDecl">];
   let Subjects = SubjectList<[LocalVar]>;
-  let Documentation = [Undocumented];
+  let Documentation = [CleanupDocs];
 }
 
 def CmseNSEntry : InheritableAttr, TargetSpecificAttr<TargetARM> {
diff --git a/clang/include/clang/Basic/AttrDocs.td b/clang/include/clang/Basic/AttrDocs.td
--- a/clang/include/clang/Basic/AttrDocs.td
+++ b/clang/include/clang/Basic/AttrDocs.td
@@ -6988,3 +6988,26 @@
 its underlying representation to be a WebAssembly ``funcref``.
   }];
 }
+
+def CleanupDocs : Documentation {
+  let Category = DocCatType;
+  let Content = [{
+This attribute allows a function to be run when a local variable goes out of
+scope. The attribute takes the identifier of a function with a parameter type
+that is a pointer to the type with the attribute.
+
+.. code-block:: c
+
+  static void foo (int *) { ... }
+  static void bar (int *) { ... }
+  void baz (void) {
+    int x __attribute__((cleanup(foo)));
+    {
+      int y __attribute__((cleanup(bar)));
+    }
+  }
+
+Will result in a call to ``bar`` then ``foo`` as ``y`` goes out of scope before
+``x``.
+}];
+}