diff --git a/jest/integration/runner/runner.js b/jest/integration/runner/runner.js
index b8da6171a26..2baaaceb849 100644
--- a/jest/integration/runner/runner.js
+++ b/jest/integration/runner/runner.js
@@ -15,6 +15,7 @@ import entrypointTemplate from './entrypoint-template';
 import {
   getBuckModeForPlatform,
   getDebugInfoFromCommandResult,
+  getFantomTestConfig,
   getShortHash,
   runBuck2,
   symbolicateStackTrace,
@@ -28,7 +29,6 @@ import path from 'path';
 
 const BUILD_OUTPUT_PATH = path.resolve(__dirname, '..', 'build');
 
-const ENABLE_OPTIMIZED_MODE: false = false;
 const PRINT_FANTOM_OUTPUT: false = false;
 
 function parseRNTesterCommandResult(result: ReturnType<typeof runBuck2>): {
@@ -95,7 +95,9 @@ module.exports = async function runTest(
 ): mixed {
   const startTime = Date.now();
 
-  const isOptimizedMode = ENABLE_OPTIMIZED_MODE;
+  const testConfig = getFantomTestConfig(testPath);
+
+  const isOptimizedMode = testConfig.mode === 'opt';
 
   const metroConfig = await Metro.loadConfig({
     config: path.resolve(__dirname, '..', 'config', 'metro.config.js'),
diff --git a/jest/integration/runner/utils.js b/jest/integration/runner/utils.js
index 3671f636afb..9e43a68f16d 100644
--- a/jest/integration/runner/utils.js
+++ b/jest/integration/runner/utils.js
@@ -12,10 +12,60 @@
 import {spawnSync} from 'child_process';
 import crypto from 'crypto';
 import fs from 'fs';
+// $FlowExpectedError[untyped-import]
+import {extract, parse} from 'jest-docblock';
 import os from 'os';
 // $FlowExpectedError[untyped-import]
 import {SourceMapConsumer} from 'source-map';
 
+type DocblockPragmas = {[key: string]: string | string[]};
+type FantomTestMode = 'dev' | 'opt';
+type FantomTestConfig = {
+  mode: FantomTestMode,
+};
+
+const DEFAULT_MODE: FantomTestMode = 'dev';
+
+/**
+ * Extracts the Fantom configuration from the test file, specified as part of
+ * the docblock comment. E.g.:
+ *
+ * ```
+ * /**
+ *  * @flow strict-local
+ *  * @fantom mode:opt
+ *  *
+ * ```
+ *
+ * So far the only supported option is `mode`, which can be 'dev' or 'opt'.
+ */
+export function getFantomTestConfig(testPath: string): FantomTestConfig {
+  const docblock = extract(fs.readFileSync(testPath, 'utf8'));
+  const pragmas = parse(docblock) as DocblockPragmas;
+
+  const config = {
+    mode: DEFAULT_MODE,
+  };
+
+  const maybeMode = pragmas.fantom_mode;
+
+  if (maybeMode != null) {
+    if (Array.isArray(maybeMode)) {
+      throw new Error('Expected a single value for @fantom_mode');
+    }
+
+    const mode = maybeMode;
+
+    if (mode === 'dev' || mode === 'opt') {
+      config.mode = mode;
+    } else {
+      throw new Error(`Invalid Fantom mode: ${mode}`);
+    }
+  }
+
+  return config;
+}
+
 export function getBuckModeForPlatform(enableRelease: boolean = false): string {
   const mode = enableRelease ? 'opt' : 'dev';