diff --git a/ReactCommon/hermes/inspector/tools/msggen/src/index.js b/ReactCommon/hermes/inspector/tools/msggen/src/index.js
index 1a137ac7170759..7952d539f30eab 100644
--- a/ReactCommon/hermes/inspector/tools/msggen/src/index.js
+++ b/ReactCommon/hermes/inspector/tools/msggen/src/index.js
@@ -197,8 +197,8 @@ function filterReachableFromRoots(
   return {types, commands, events};
 }
 
-function main() {
-  const args = yargs
+async function main(): Promise<void> {
+  const args = await yargs
     .usage('Usage: msggen <header_path> <cpp_path>')
     .alias('h', 'help')
     .help('h')
diff --git a/flow-typed/npm/yargs_v17.x.x.js b/flow-typed/npm/yargs_v17.x.x.js
new file mode 100644
index 00000000000000..2750236797a305
--- /dev/null
+++ b/flow-typed/npm/yargs_v17.x.x.js
@@ -0,0 +1,341 @@
+// flow-typed signature: cab38813101e0a162deaae556391abc8
+// flow-typed version: f7c859e705/yargs_v17.x.x/flow_>=v0.104.x
+
+declare module "yargs" {
+  declare type Argv = {
+    [key: string]: any,
+    _: Array<string>,
+    $0: string,
+    ...
+  };
+
+  declare type Options = $Shape<{
+    alias: string | Array<string>,
+    array: boolean,
+    boolean: boolean,
+    choices: Array<mixed>,
+    coerce: (arg: {[key: string]: any, ...} | any) => mixed,
+    config: boolean,
+    configParser: (configPath: string) => { [key: string]: mixed, ... },
+    conflicts: string | Array<string> | { [key: string]: string, ... },
+    count: boolean,
+    default: mixed,
+    defaultDescription: string,
+    demandOption: boolean | string,
+    desc: string,
+    describe: string,
+    description: string,
+    global: boolean,
+    group: string,
+    hidden: boolean,
+    implies: string | { [key: string]: string, ... },
+    nargs: number,
+    normalize: boolean,
+    number: boolean,
+    required: boolean,
+    requiresArg: boolean,
+    skipValidation: boolean,
+    string: boolean,
+    type: "array" | "boolean" | "count" | "number" | "string",
+    ...
+  }>;
+
+  declare type CommonModuleObject = {|
+    command?: string | Array<string>,
+    aliases?: Array<string> | string,
+    builder?: { [key: string]: Options, ... } | ((yargsInstance: Yargs) => mixed),
+    handler?: ((argv: Argv) => void) | ((argv: Argv) => Promise<void>)
+  |};
+
+  declare type ModuleObjectDesc = {|
+    ...CommonModuleObject,
+    desc?: string | false
+  |};
+
+  declare type ModuleObjectDescribe = {|
+    ...CommonModuleObject,
+    describe?: string | false
+  |};
+
+  declare type ModuleObjectDescription = {|
+    ...CommonModuleObject,
+    description?: string | false
+  |};
+
+  declare type ModuleObject =
+    | ModuleObjectDesc
+    | ModuleObjectDescribe
+    | ModuleObjectDescription;
+
+  declare type MiddleWareCallback =
+    | (argv: Argv, yargsInstance?: Yargs) => void
+    | (argv: Argv, yargsInstance?: Yargs) => Promise<void>;
+
+  declare type Middleware = MiddleWareCallback | Array<MiddleWareCallback>;
+
+  declare class Yargs {
+    (args: Array<string>): Yargs;
+
+    alias(key: string, alias: string): this;
+    alias(alias: { [key: string]: string | Array<string>, ... }): this;
+    argv: Argv | Promise<Argv>;
+    array(key: string | Array<string>): this;
+    boolean(parameter: string | Array<string>): this;
+    check(fn: (argv: Argv, options: Array<string>) => mixed): this;
+    choices(key: string, allowed: Array<string>): this;
+    choices(allowed: { [key: string]: Array<string>, ... }): this;
+    coerce(key: string, fn: (value: any) => mixed): this;
+    coerce(object: { [key: string]: (value: any) => mixed, ... }): this;
+    coerce(keys: Array<string>, fn: (value: any) => mixed): this;
+
+    command(
+      cmd: string | Array<string>,
+      desc: string | false,
+      builder?:
+        | { [key: string]: Options, ... }
+        | ((yargsInstance: Yargs) => mixed),
+      handler?: Function
+    ): this;
+    command(
+      cmd: string | Array<string>,
+      desc: string | false,
+      module: ModuleObject
+    ): this;
+    command(module: ModuleObject): this;
+
+    commands(
+      cmd: string | Array<string>,
+      desc: string | false,
+      builder?:
+        | { [key: string]: Options, ... }
+        | ((yargsInstance: Yargs) => mixed),
+      handler?: Function
+    ): this;
+    commands(
+      cmd: string | Array<string>,
+      desc: string | false,
+      module: ModuleObject
+    ): this;
+    commands(module: ModuleObject): this;
+
+    commandDir(
+      directory: string,
+      options?: {
+        exclude?: string | Function,
+        extensions?: Array<string>,
+        include?: string | Function,
+        recurse?: boolean,
+        visit?: Function,
+        ...
+      },
+    ): this;
+
+    completion(
+      cmd?: string,
+      description?: string | false | (
+        current: string,
+        argv: Argv,
+        done: (compeltion: Array<string>) => void
+      ) => ?(Array<string> | Promise<Array<string>>),
+      fn?: (
+        current: string,
+        argv: Argv,
+        done: (completion: Array<string>) => void
+      ) => ?(Array<string> | Promise<Array<string>>)
+    ): this;
+
+    config(
+      key?: string,
+      description?: string,
+      parseFn?: (configPath: string) => { [key: string]: mixed, ... }
+    ): this;
+    config(
+      key: string,
+      parseFn?: (configPath: string) => { [key: string]: mixed, ... }
+    ): this;
+    config(config: { [key: string]: mixed, ... }): this;
+
+    conflicts(key: string, value: string | Array<string>): this;
+    conflicts(keys: { [key: string]: string | Array<string>, ... }): this;
+
+    count(name: string): this;
+
+    default(key: string, value: mixed, description?: string): this;
+    default(defaults: { [key: string]: mixed, ... }): this;
+
+    // Deprecated: use demandOption() and demandCommand() instead.
+    demand(key: string, msg?: string | boolean): this;
+    demand(count: number, max?: number, msg?: string | boolean): this;
+
+    demandOption(key: string | Array<string>, msg?: string | boolean): this;
+
+    demandCommand(): this;
+    demandCommand(min: number, minMsg?: string): this;
+    demandCommand(
+      min: number,
+      max: number,
+      minMsg?: string,
+      maxMsg?: string
+    ): this;
+
+    describe(key: string, description: string): this;
+    describe(describeObject: { [key: string]: string, ... }): this;
+
+    detectLocale(shouldDetect: boolean): this;
+
+    env(prefix?: string): this;
+
+    epilog(text: string): this;
+    epilogue(text: string): this;
+
+    example(cmd: string, desc?: string): this;
+
+    exitProcess(enable: boolean): this;
+
+    fail(fn: (failureMessage: string, err: Error, yargs: Yargs) => mixed): this;
+
+    getCompletion(
+      args: Array<string>,
+      fn: (err: Error | null, completions: Array<string> | void) => void
+    ): Promise<Array<string> | void>;
+
+    global(globals: string | Array<string>, isGlobal?: boolean): this;
+
+    group(key: string | Array<string>, groupName: string): this;
+
+    help(option: boolean): this;
+
+    help(option?: string, desc?: string): this;
+
+    hide(key: string): this;
+
+    implies(key: string, value: string | Array<string>): this;
+    implies(keys: { [key: string]: string | Array<string>, ... }): this;
+
+    locale(
+      locale: | "de"
+      | "en"
+      | "es"
+      | "fr"
+      | "hi"
+      | "hu"
+      | "id"
+      | "it"
+      | "ja"
+      | "ko"
+      | "nb"
+      | "pirate"
+      | "pl"
+      | "pt"
+      | "pt_BR"
+      | "ru"
+      | "th"
+      | "tr"
+      | "zh_CN"
+    ): this;
+    locale(): string;
+
+    middleware(
+      middlewareCallbacks: Middleware,
+      applyBeforeValidation?: boolean,
+    ): this;
+
+    nargs(key: string, count: number): this;
+
+    normalize(key: string): this;
+
+    number(key: string | Array<string>): this;
+
+    option(key: string, options?: Options): this;
+    option(optionMap: { [key: string]: Options, ... }): this;
+
+    options(key: string, options?: Options): this;
+    options(optionMap: { [key: string]: Options, ... }): this;
+
+    parse(
+      args?: string | Array<string>,
+      context?: { [key: string]: any, ... },
+      parseCallback?: (err: Error, argv: Argv, output?: string) => void
+    ): Argv | Promise<Argv>;
+    parse(
+      args?: string | Array<string>,
+      parseCallback?: (err: Error, argv: Argv, output?: string) => void
+    ): Argv | Promise<Argv>;
+
+    parseAsync(
+      args?: string | Array<string>,
+      context?: { [key: string]: any, ... },
+      parseCallback?: (err: Error, argv: Argv, output?: string) => void
+    ): Promise<Argv>;
+    parseAsync(
+      args?: string | Array<string>,
+      parseCallback?: (err: Error, argv: Argv, output?: string) => void
+    ): Promise<Argv>;
+
+    parseSync(
+      args?: string | Array<string>,
+      context?: { [key: string]: any, ... },
+      parseCallback?: (err: Error, argv: Argv, output?: string) => void
+    ): Argv;
+    parseSync(
+      args?: string | Array<string>,
+      parseCallback?: (err: Error, argv: Argv, output?: string) => void
+    ): Argv;
+
+    parserConfiguration(configuration: {[key: string]: any, ...}): this;
+
+    pkgConf(key: string, cwd?: string): this;
+
+    positional(key: string, opt?: Options): this;
+
+    recommendCommands(): this;
+
+    // Alias of demand()
+    require(key: string, msg: string | boolean): this;
+    require(count: number, max?: number, msg?: string | boolean): this;
+
+    requiresArg(key: string | Array<string>): this;
+
+    scriptName(name: string): this;
+
+    showCompletionScript(): this;
+
+    showHelp(consoleLevel?: "error" | "warn" | "log"): this;
+    showHelp(printCallback: (usageData: string) => void): this;
+
+    showHelpOnFail(enable: boolean, message?: string): this;
+
+    skipValidation(key: string): this;
+
+    showVersion(consoleLevel?: "error" | "warn" | "log"): this;
+    showVersion(printCallback: (usageData: string) => void): this;
+
+    strict(enabled?: boolean): this;
+
+    strictCommands(enabled?: boolean): this;
+
+    strictOptions(enabled?: boolean): this;
+
+    string(key: string | Array<string>): this;
+
+    terminalWidth(): number;
+
+    updateLocale(obj: { [key: string]: string, ... }): this;
+    updateStrings(obj: { [key: string]: string, ... }): this;
+
+    usage(message: string, opts?: { [key: string]: Options, ... }): this;
+
+    version(): this;
+    version(version: string | false): this;
+    version(option: string | (() => string), version: string): this;
+    version(
+      option: string | (() => string),
+      description: string | (() => string),
+      version: string
+    ): this;
+
+    wrap(columns: number | null): this;
+  }
+
+  declare module.exports: Yargs;
+}