diff --git a/flow/fbjs.js b/flow/fbjs.js
new file mode 100644
index 00000000000..15f3e0d3995
--- /dev/null
+++ b/flow/fbjs.js
@@ -0,0 +1,258 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @flow strict
+ * @format
+ * @nolint
+ */
+
+declare module 'fbjs/lib/countDistinct' {
+  declare module.exports: {|
+    <T1, T2>(iter: Iterable<T1>, selector: (item: T1) => T2): number,
+  |};
+}
+
+declare module 'fbjs/lib/warning' {
+  declare module.exports: {|
+    (condition: mixed, format: string, ...args: $ReadOnlyArray<mixed>): void,
+  |};
+}
+
+declare module 'fbjs/lib/shallowEqual' {
+  declare module.exports: {|
+    (objA: mixed, objB: mixed): boolean,
+  |};
+}
+
+declare module 'fbjs/lib/EventListener' {
+  declare module.exports: {|
+    listen(
+      target: EventTarget,
+      eventType: string,
+      callback: any,
+    ): {remove(): void, ...},
+    capture(
+      target: EventTarget,
+      eventType: string,
+      callback: any,
+    ): {remove(): void, ...},
+  |};
+}
+
+declare module 'fbjs/lib/ExecutionEnvironment' {
+  declare module.exports: {|
+    +canUseDOM: boolean,
+    +canUseWorkers: boolean,
+    +canUseEventListeners: boolean,
+    +canUseViewport: boolean,
+    +isInWorker: boolean,
+  |};
+}
+
+declare module 'fbjs/lib/UserAgentData' {
+  declare module.exports: {|
+    +browserArchitecture: string,
+    +browserFullVersion: string,
+    +browserMinorVersion: string,
+    +browserName: string,
+    +browserVersion: string,
+    +deviceName: string,
+    +engineName: string,
+    +engineVersion: string,
+    +platformArchitecture: string,
+    +platformName: string,
+    +platformVersion: string,
+    +platformFullVersion: string,
+  |};
+}
+
+declare module 'fbjs/lib/VersionRange' {
+  declare module.exports: {|
+    contains(range: string, version: string): boolean,
+  |};
+}
+
+declare module 'fbjs/lib/base62' {
+  declare module.exports: {|
+    (number: number): string,
+  |};
+}
+
+declare module 'fbjs/lib/compactArray' {
+  declare module.exports: {|
+    <T>(array: Array<T | null | void>): Array<T>,
+  |};
+}
+
+declare module 'fbjs/lib/concatAllArray' {
+  declare module.exports: any;
+}
+
+declare module 'fbjs/lib/crc32' {
+  declare module.exports: {|
+    (str: string): number,
+  |};
+}
+
+declare module 'fbjs/lib/distinctArray' {
+  declare module.exports: {|
+    <T>(xs: Iterable<T>): Array<T>,
+  |};
+}
+
+declare module 'fbjs/lib/emptyObject' {
+  declare module.exports: {||};
+}
+
+declare module 'fbjs/lib/equalsSet' {
+  declare module.exports: {|
+    <T>(one: Set<T>, two: Set<T>): boolean,
+  |};
+}
+
+declare module 'fbjs/lib/everyObject' {
+  declare module.exports: {|
+    (
+      object: mixed,
+      callback: (value: any, name: string, object: mixed) => any,
+      context?: any,
+    ): boolean,
+  |};
+}
+
+declare module 'fbjs/lib/everySet' {
+  declare module.exports: {|
+    <T>(
+      object: ?Set<T>,
+      callback: (value: any, name: string, object: Set<T>) => any,
+      context?: any,
+    ): boolean,
+  |};
+}
+
+declare module 'fbjs/lib/filterObject' {
+  declare module.exports: any;
+}
+
+declare module 'fbjs/lib/forEachObject' {
+  declare module.exports: any;
+}
+
+declare module 'fbjs/lib/groupArray' {
+  declare module.exports: any;
+}
+
+declare module 'fbjs/lib/joinClasses' {
+  declare module.exports: {|
+    (className: mixed): string,
+  |};
+}
+
+declare module 'fbjs/lib/keyMirrorRecursive' {
+  declare module.exports: any;
+}
+
+declare module 'fbjs/lib/keyOf' {
+  declare module.exports: any;
+}
+
+declare module 'fbjs/lib/maxBy' {
+  declare module.exports: {|
+    <A, B>(
+      as: Iterable<A>,
+      f: (a: A) => B,
+      compare?: ?(u: B, v: B) => number,
+    ): ?A,
+  |};
+}
+
+declare module 'fbjs/lib/memoizeStringOnly' {
+  declare module.exports: {|
+    <T>(callback: (s: string) => T): (s: string) => T,
+  |};
+}
+
+declare module 'fbjs/lib/minBy' {
+  declare module.exports: {|
+    <A, B>(
+      as: Iterable<A>,
+      f: (a: A) => B,
+      compare?: ?(u: B, v: B) => number,
+    ): ?A,
+  |};
+}
+
+declare module 'fbjs/lib/partitionArray' {
+  declare module.exports: {|
+    <Tv>(
+      array: Array<Tv>,
+      predicate: (value: Tv, index: number, array: Array<Tv>) => boolean,
+      context?: any,
+    ): [Array<Tv>, Array<Tv>],
+  |};
+}
+
+declare module 'fbjs/lib/partitionObject' {
+  declare module.exports: {|
+    <Tv>(
+      object: {[key: string]: Tv, ...},
+      callback: (
+        value: Tv,
+        key: string,
+        object: {[key: string]: Tv, ...},
+      ) => boolean,
+      context?: any,
+    ): [{[key: string]: Tv, ...}, {[key: string]: Tv, ...}],
+  |};
+}
+
+declare module 'fbjs/lib/partitionObjectByKey' {
+  declare module.exports: any;
+}
+
+declare module 'fbjs/lib/performance' {
+  declare module.exports: any;
+}
+
+declare module 'fbjs/lib/performanceNow' {
+  declare module.exports: any;
+}
+
+declare module 'fbjs/lib/requestAnimationFrame' {
+  declare module.exports: any;
+}
+
+declare module 'fbjs/lib/someObject' {
+  declare module.exports: {|
+    (
+      object: mixed,
+      callback: (value: any, name: string, object: mixed) => any,
+      context?: any,
+    ): boolean,
+  |};
+}
+
+declare module 'fbjs/lib/someSet' {
+  declare module.exports: {|
+    <T>(
+      set: Set<T>,
+      callback: (value: T, key: T, set: Set<T>) => boolean,
+      context?: any,
+    ): boolean,
+  |};
+}
+
+declare module 'fbjs/lib/keyMirror' {
+  declare module.exports: {|
+    <T: {...}>(obj: T): $ObjMapi<T, <K>(K) => K>,
+  |};
+}
+
+declare module 'fbjs/lib/invariant' {
+  declare module.exports: {|
+    (condition: mixed, format: string, ...args: Array<mixed>): void,
+  |};
+}
diff --git a/flow/use-subscription.js b/flow/use-subscription.js
new file mode 100644
index 00000000000..4b555c3b60e
--- /dev/null
+++ b/flow/use-subscription.js
@@ -0,0 +1,19 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @flow strict
+ * @format
+ * @nolint
+ */
+
+'use strict';
+
+declare module 'use-subscription' {
+  declare export function useSubscription<Value>(subscription: {|
+    getCurrentValue: () => Value,
+    subscribe: (callback: Function) => () => void,
+  |}): Value;
+}