diff --git a/repo-config/package.json b/repo-config/package.json
index ae56af9bbc495c..b16cb4e29627c9 100644
--- a/repo-config/package.json
+++ b/repo-config/package.json
@@ -40,6 +40,7 @@
     "jest-junit": "^10.0.0",
     "jscodeshift": "^0.13.1",
     "metro-babel-register": "0.70.3",
+    "metro-memory-fs": "0.70.2",
     "mkdirp": "^0.5.1",
     "prettier": "^2.4.1",
     "react": "18.0.0",
diff --git a/scripts/__tests__/hermes-utils-test.js b/scripts/__tests__/hermes-utils-test.js
new file mode 100644
index 00000000000000..6044afab155b59
--- /dev/null
+++ b/scripts/__tests__/hermes-utils-test.js
@@ -0,0 +1,242 @@
+/**
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @format
+ */
+
+import * as path from 'path';
+
+const {
+  copyBuildScripts,
+  downloadHermesTarball,
+  expandHermesTarball,
+  getHermesTagSHA,
+  readHermesTag,
+  setHermesTag,
+} = require('../hermes/hermes-utils');
+
+const hermesTag =
+  'hermes-2022-04-28-RNv0.69.0-15d07c2edd29a4ea0b8f15ab0588a0c1adb1200f';
+const tarballContents = 'dummy string';
+const hermesTagSha = '5244f819b2f3949ca94a3a1bf75d54a8ed59d94a';
+
+const ROOT_DIR = path.normalize(path.join(__dirname, '..', '..'));
+const SDKS_DIR = path.join(ROOT_DIR, 'sdks');
+
+let execCalls;
+let fs;
+let shelljs;
+
+jest.mock('shelljs', () => ({
+  echo: jest.fn(),
+  exec: jest.fn(command => {
+    if (command.startsWith('curl')) {
+      fs.writeFileSync(
+        path.join(SDKS_DIR, 'download', `hermes-${hermesTagSha}.tgz`),
+        tarballContents,
+      );
+      execCalls.curl = true;
+      return {code: 0};
+    }
+
+    if (command.startsWith('git')) {
+      execCalls.git = true;
+      return hermesTagSha + '\n';
+    }
+
+    if (command.startsWith('tar')) {
+      fs.mkdirSync(path.join(SDKS_DIR, 'hermes', 'utils'), {
+        recursive: true,
+      });
+      fs.writeFileSync(path.join(SDKS_DIR, 'hermes', `package.json`), '{}');
+      execCalls.tar = true;
+      return {code: 0};
+    }
+  }),
+  exit: jest.fn(),
+}));
+
+function populateMockFilesystem() {
+  fs.mkdirSync(path.join(SDKS_DIR, 'hermes-engine', 'utils'), {
+    recursive: true,
+  });
+  fs.writeFileSync(
+    path.join(
+      ROOT_DIR,
+      'sdks',
+      'hermes-engine',
+      'utils',
+      'build-apple-framework.sh',
+    ),
+    'Dummy file',
+  );
+  fs.writeFileSync(
+    path.join(
+      ROOT_DIR,
+      'sdks',
+      'hermes-engine',
+      'utils',
+      'build-ios-framework.sh',
+    ),
+    'Dummy file',
+  );
+  fs.writeFileSync(
+    path.join(
+      ROOT_DIR,
+      'sdks',
+      'hermes-engine',
+      'utils',
+      'build-mac-framework.sh',
+    ),
+    'Dummy file',
+  );
+  fs.writeFileSync(
+    path.join(SDKS_DIR, 'hermes-engine', 'hermes-engine.podspec'),
+    'Dummy file',
+  );
+}
+
+describe('hermes-utils', () => {
+  beforeEach(() => {
+    jest.resetModules();
+
+    jest.mock('fs', () => new (require('metro-memory-fs'))());
+    fs = require('fs');
+    fs.reset();
+
+    populateMockFilesystem();
+
+    execCalls = Object.create(null);
+    shelljs = require('shelljs');
+  });
+  describe('readHermesTag', () => {
+    it('should return main if .hermesversion does not exist', () => {
+      expect(readHermesTag()).toEqual('main');
+    });
+    it('should return tag from .hermesversion if file exists', () => {
+      fs.writeFileSync(path.join(SDKS_DIR, '.hermesversion'), hermesTag);
+      expect(readHermesTag()).toEqual(hermesTag);
+    });
+  });
+  describe('setHermesTag', () => {
+    it('should write tag to .hermesversion file', () => {
+      setHermesTag(hermesTag);
+      expect(
+        fs.readFileSync(path.join(SDKS_DIR, '.hermesversion'), {
+          encoding: 'utf8',
+          flag: 'r',
+        }),
+      ).toEqual(hermesTag);
+    });
+    it('should set Hermes tag and read it back', () => {
+      setHermesTag(hermesTag);
+      expect(readHermesTag()).toEqual(hermesTag);
+    });
+  });
+  describe('getHermesTagSHA', () => {
+    it('should return trimmed commit SHA for Hermes tag', () => {
+      expect(getHermesTagSHA(hermesTag)).toEqual(hermesTagSha);
+      expect(execCalls.git).toBeTruthy();
+    });
+  });
+  describe('downloadHermesTarball', () => {
+    it('should download Hermes tarball to download dir', () => {
+      downloadHermesTarball();
+      expect(execCalls.curl).toBeTruthy();
+      expect(
+        fs.readFileSync(
+          path.join(SDKS_DIR, 'download', `hermes-${hermesTagSha}.tgz`),
+          {
+            encoding: 'utf8',
+            flag: 'r',
+          },
+        ),
+      ).toEqual(tarballContents);
+    });
+    it('should not re-download Hermes tarball if tarball exists', () => {
+      fs.mkdirSync(path.join(SDKS_DIR, 'download'), {recursive: true});
+      fs.writeFileSync(
+        path.join(SDKS_DIR, 'download', `hermes-${hermesTagSha}.tgz`),
+        tarballContents,
+      );
+
+      downloadHermesTarball();
+      expect(execCalls.curl).toBeUndefined();
+    });
+  });
+  describe('expandHermesTarball', () => {
+    it('should expand Hermes tarball to Hermes source dir', () => {
+      fs.mkdirSync(path.join(SDKS_DIR, 'download'), {recursive: true});
+      fs.writeFileSync(
+        path.join(SDKS_DIR, 'download', `hermes-${hermesTagSha}.tgz`),
+        tarballContents,
+      );
+      expect(fs.existsSync(path.join(SDKS_DIR, 'hermes'))).toBeFalsy();
+      expandHermesTarball();
+      expect(execCalls.tar).toBe(true);
+      expect(fs.existsSync(path.join(SDKS_DIR, 'hermes'))).toBeTruthy();
+    });
+    it('should fail if Hermes tarball does not exist', () => {
+      expandHermesTarball();
+      expect(execCalls.tar).toBeUndefined();
+      expect(shelljs.exit.mock.calls.length).toBeGreaterThan(0);
+    });
+  });
+  describe('copyBuildScripts', () => {
+    it('should copy React Native Hermes build scripts to Hermes source directory', () => {
+      fs.mkdirSync(path.join(SDKS_DIR, 'hermes', 'utils'), {
+        recursive: true,
+      });
+      copyBuildScripts();
+      expect(
+        fs.readFileSync(
+          path.join(
+            ROOT_DIR,
+            'sdks',
+            'hermes',
+            'utils',
+            'build-mac-framework.sh',
+          ),
+          {
+            encoding: 'utf8',
+            flag: 'r',
+          },
+        ),
+      ).toEqual(
+        fs.readFileSync(
+          path.join(
+            ROOT_DIR,
+            'sdks',
+            'hermes-engine',
+            'utils',
+            'build-mac-framework.sh',
+          ),
+          {
+            encoding: 'utf8',
+            flag: 'r',
+          },
+        ),
+      );
+      expect(
+        fs.readFileSync(
+          path.join(SDKS_DIR, 'hermes', 'hermes-engine.podspec'),
+          {
+            encoding: 'utf8',
+            flag: 'r',
+          },
+        ),
+      ).toEqual(
+        fs.readFileSync(
+          path.join(SDKS_DIR, 'hermes-engine', 'hermes-engine.podspec'),
+          {
+            encoding: 'utf8',
+            flag: 'r',
+          },
+        ),
+      );
+    });
+  });
+});
diff --git a/scripts/hermes/hermes-utils.js b/scripts/hermes/hermes-utils.js
index 5729a3ec83ab7a..1cbbc7b979e8dc 100644
--- a/scripts/hermes/hermes-utils.js
+++ b/scripts/hermes/hermes-utils.js
@@ -66,7 +66,7 @@ function getHermesTagSHA(hermesTag) {
 
 function getHermesTarballDownloadPath(hermesTag) {
   const hermesTagSHA = getHermesTagSHA(hermesTag);
-  return `${HERMES_TARBALL_DOWNLOAD_DIR}/hermes-${hermesTagSHA}.tgz`;
+  return path.join(HERMES_TARBALL_DOWNLOAD_DIR, `hermes-${hermesTagSHA}.tgz`);
 }
 
 function downloadHermesTarball() {
@@ -117,21 +117,29 @@ function expandHermesTarball() {
 }
 
 function copyBuildScripts() {
+  if (!fs.existsSync(HERMES_DIR)) {
+    echo(
+      '[Hermes] Failed to copy Hermes build scripts, no Hermes source directory found.',
+    );
+    exit(1);
+    return;
+  }
+
   fs.copyFileSync(
-    `${SDKS_DIR}/hermes-engine/hermes-engine.podspec`,
-    `${HERMES_DIR}/hermes-engine.podspec`,
+    path.join(SDKS_DIR, 'hermes-engine', 'hermes-engine.podspec'),
+    path.join(HERMES_DIR, 'hermes-engine.podspec'),
   );
   fs.copyFileSync(
-    `${SDKS_DIR}/hermes-engine/utils/build-apple-framework.sh`,
-    `${HERMES_DIR}/utils/build-apple-framework.sh`,
+    path.join(SDKS_DIR, 'hermes-engine', 'utils', 'build-apple-framework.sh'),
+    path.join(HERMES_DIR, 'utils', 'build-apple-framework.sh'),
   );
   fs.copyFileSync(
-    `${SDKS_DIR}/hermes-engine/utils/build-ios-framework.sh`,
-    `${HERMES_DIR}/utils/build-ios-framework.sh`,
+    path.join(SDKS_DIR, 'hermes-engine', 'utils', 'build-ios-framework.sh'),
+    path.join(HERMES_DIR, 'utils', 'build-ios-framework.sh'),
   );
   fs.copyFileSync(
-    `${SDKS_DIR}/hermes-engine/utils/build-mac-framework.sh`,
-    `${HERMES_DIR}/utils/build-mac-framework.sh`,
+    path.join(SDKS_DIR, 'hermes-engine', 'utils', 'build-mac-framework.sh'),
+    path.join(HERMES_DIR, 'utils', 'build-mac-framework.sh'),
   );
 }
 
diff --git a/yarn.lock b/yarn.lock
index 7a8c6fcf0f1ab1..806d9d039b5501 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -4973,6 +4973,11 @@ metro-inspector-proxy@0.70.3:
     ws "^7.5.1"
     yargs "^15.3.1"
 
+metro-memory-fs@0.70.2:
+  version "0.70.2"
+  resolved "https://registry.yarnpkg.com/metro-memory-fs/-/metro-memory-fs-0.70.2.tgz#abf175204e37aae7f4eec712a24644af950a4b16"
+  integrity sha512-fLMvoh4vkYRi5SvDDgTJSOCt5PIGL1nhvcxrKSBmE9UZvhjPFMmkBHVrWuVUpmamzP0PCwCWTcabFlCkl4HvUw==
+
 metro-minify-uglify@0.70.3:
   version "0.70.3"
   resolved "https://registry.yarnpkg.com/metro-minify-uglify/-/metro-minify-uglify-0.70.3.tgz#2f28129ca5b8ef958f3e3fcf004c3707c7732e1e"