diff --git a/primitives/api/proc-macro/src/impl_runtime_apis.rs b/primitives/api/proc-macro/src/impl_runtime_apis.rs
index f594a743fcf94..f1903191e712f 100644
--- a/primitives/api/proc-macro/src/impl_runtime_apis.rs
+++ b/primitives/api/proc-macro/src/impl_runtime_apis.rs
@@ -301,6 +301,10 @@ fn generate_runtime_api_base_structures() -> Result<TokenStream> {
 					state_version,
 				)
 			}
+
+			fn overlay(&self) -> #crate_::OverlayedChanges {
+				::std::clone::Clone::clone(&::std::cell::RefCell::borrow(&self.changes))
+			}
 		}
 
 		#[cfg(any(feature = "std", test))]
diff --git a/primitives/api/proc-macro/src/mock_impl_runtime_apis.rs b/primitives/api/proc-macro/src/mock_impl_runtime_apis.rs
index ffc158ac94d29..ce955405873f2 100644
--- a/primitives/api/proc-macro/src/mock_impl_runtime_apis.rs
+++ b/primitives/api/proc-macro/src/mock_impl_runtime_apis.rs
@@ -123,6 +123,10 @@ fn implement_common_api_traits(block_type: TypePath, self_ty: Type) -> Result<To
 			> where Self: Sized {
 				unimplemented!("`into_storage_changes` not implemented for runtime api mocks")
 			}
+
+			fn overlay(&self) -> #crate_::OverlayedChanges {
+				unimplemented!("`overlay` not implemented for runtime api mocks")
+			}
 		}
 
 		impl #crate_::Core<#block_type> for #self_ty {
diff --git a/primitives/api/src/lib.rs b/primitives/api/src/lib.rs
index 964ef15ce5f5a..5c109d6fb46ac 100644
--- a/primitives/api/src/lib.rs
+++ b/primitives/api/src/lib.rs
@@ -519,6 +519,11 @@ pub trait ApiExt<Block: BlockT> {
 	) -> Result<StorageChanges<Self::StateBackend, Block>, String>
 	where
 		Self: Sized;
+
+	/// Returns the overlayed changes.
+	///
+	/// Useful when you want to construct an intermediate state during the entire block execution.
+	fn overlay(&self) -> OverlayedChanges;
 }
 
 /// Parameters for [`CallApiAt::call_api_at`].