diff --git a/ReactAndroid/src/main/java/com/facebook/react/devsupport/DevInternalSettings.java b/ReactAndroid/src/main/java/com/facebook/react/devsupport/DevInternalSettings.java
index ca3558939..65f71e503 100644
--- a/ReactAndroid/src/main/java/com/facebook/react/devsupport/DevInternalSettings.java
+++ b/ReactAndroid/src/main/java/com/facebook/react/devsupport/DevInternalSettings.java
@@ -29,6 +29,7 @@ public class DevInternalSettings implements
     SharedPreferences.OnSharedPreferenceChangeListener {
 
   private static final String PREFS_FPS_DEBUG_KEY = "fps_debug";
+  private static final String PREFS_JS_DEV_MODE_DEBUG_KEY = "js_dev_mode_debug";
   private static final String PREFS_DEBUG_SERVER_HOST_KEY = "debug_http_host";
   private static final String PREFS_ANIMATIONS_DEBUG_KEY = "animations_debug";
   private static final String PREFS_RELOAD_ON_JS_CHANGE_KEY = "reload_on_js_change";
@@ -54,12 +55,19 @@ public class DevInternalSettings implements
     return mPreferences.getBoolean(PREFS_ANIMATIONS_DEBUG_KEY, false);
   }
 
+  @Override
+  public boolean isJSDevModeEnabled() {
+    return mPreferences.getBoolean(PREFS_JS_DEV_MODE_DEBUG_KEY, true);
+  }
+
   public @Nullable String getDebugServerHost() {
     return mPreferences.getString(PREFS_DEBUG_SERVER_HOST_KEY, null);
   }
 
   public void onSharedPreferenceChanged(SharedPreferences sharedPreferences, String key) {
-    if (PREFS_FPS_DEBUG_KEY.equals(key) || PREFS_RELOAD_ON_JS_CHANGE_KEY.equals(key)) {
+    if (PREFS_FPS_DEBUG_KEY.equals(key) ||
+        PREFS_RELOAD_ON_JS_CHANGE_KEY.equals(key) ||
+        PREFS_JS_DEV_MODE_DEBUG_KEY.equals(key)) {
       mDebugManager.reloadSettings();
     }
   }
diff --git a/ReactAndroid/src/main/java/com/facebook/react/devsupport/DevServerHelper.java b/ReactAndroid/src/main/java/com/facebook/react/devsupport/DevServerHelper.java
index 99a9da485..a91312b73 100644
--- a/ReactAndroid/src/main/java/com/facebook/react/devsupport/DevServerHelper.java
+++ b/ReactAndroid/src/main/java/com/facebook/react/devsupport/DevServerHelper.java
@@ -54,7 +54,7 @@ import okio.Sink;
   private static final String DEVICE_LOCALHOST = "localhost";
 
   private static final String BUNDLE_URL_FORMAT =
-      "http://%s:8081/%s.bundle?platform=android";
+      "http://%s:8081/%s.bundle?platform=android&dev=%s";
   private static final String SOURCE_MAP_URL_FORMAT =
       BUNDLE_URL_FORMAT.replaceFirst("\\.bundle", ".map");
   private static final String LAUNCH_CHROME_DEVTOOLS_COMMAND_URL_FORMAT =
@@ -111,6 +111,13 @@ import okio.Sink;
     return "localhost";
   }
 
+  /**
+   * @return whether we should enabled dev mode or not when requesting JS bundles.
+   */
+  private boolean getDevMode() {
+    return mSettings.isJSDevModeEnabled();
+  }
+
   /**
    * @return the host to use when connecting to the bundle server.
    */
@@ -145,15 +152,15 @@ import okio.Sink;
     return Build.FINGERPRINT.contains("generic");
   }
 
-  private String createBundleURL(String host, String jsModulePath) {
-    return String.format(BUNDLE_URL_FORMAT, host, jsModulePath);
+  private String createBundleURL(String host, String jsModulePath, boolean devMode) {
+    return String.format(BUNDLE_URL_FORMAT, host, jsModulePath, devMode);
   }
 
   public void downloadBundleFromURL(
       final BundleDownloadCallback callback,
       final String jsModulePath,
       final File outputFile) {
-    final String bundleURL = createBundleURL(getDebugServerHost(), jsModulePath);
+    final String bundleURL = createBundleURL(getDebugServerHost(), jsModulePath, getDevMode());
     Request request = new Request.Builder()
         .url(bundleURL)
         .build();
@@ -288,17 +295,17 @@ import okio.Sink;
   }
 
   public String getSourceMapUrl(String mainModuleName) {
-    return String.format(Locale.US, SOURCE_MAP_URL_FORMAT, getDebugServerHost(), mainModuleName);
+    return String.format(Locale.US, SOURCE_MAP_URL_FORMAT, getDebugServerHost(), mainModuleName, getDevMode());
   }
 
   public String getSourceUrl(String mainModuleName) {
-    return String.format(Locale.US, BUNDLE_URL_FORMAT, getDebugServerHost(), mainModuleName);
+    return String.format(Locale.US, BUNDLE_URL_FORMAT, getDebugServerHost(), mainModuleName, getDevMode());
   }
 
   public String getJSBundleURLForRemoteDebugging(String mainModuleName) {
     // The host IP we use when connecting to the JS bundle server from the emulator is not the
     // same as the one needed to connect to the same server from the Chrome proxy running on the
     // host itself.
-    return createBundleURL(getHostForJSProxy(), mainModuleName);
+    return createBundleURL(getHostForJSProxy(), mainModuleName, getDevMode());
   }
 }
diff --git a/ReactAndroid/src/main/java/com/facebook/react/modules/debug/DeveloperSettings.java b/ReactAndroid/src/main/java/com/facebook/react/modules/debug/DeveloperSettings.java
index 2ecad91c3..13a230fc3 100644
--- a/ReactAndroid/src/main/java/com/facebook/react/modules/debug/DeveloperSettings.java
+++ b/ReactAndroid/src/main/java/com/facebook/react/modules/debug/DeveloperSettings.java
@@ -23,4 +23,9 @@ public interface DeveloperSettings {
    * @return Whether debug information about transitions should be displayed.
    */
   boolean isAnimationFpsDebugEnabled();
+
+  /**
+   * @return Whether dev mode should be enabled in JS bundles.
+   */
+  boolean isJSDevModeEnabled();
 }
diff --git a/ReactAndroid/src/main/res/devsupport/xml/preferences.xml b/ReactAndroid/src/main/res/devsupport/xml/preferences.xml
index 4eca11330..f7eb6a5fb 100644
--- a/ReactAndroid/src/main/res/devsupport/xml/preferences.xml
+++ b/ReactAndroid/src/main/res/devsupport/xml/preferences.xml
@@ -7,6 +7,12 @@
       android:key="catalyst_perf"
       android:title="Performance"
       >
+    <CheckBoxPreference
+        android:key="js_dev_mode_debug"
+        android:title="JS Dev Mode"
+        android:summary="Load JavaScript bundle with __DEV__ = true for easier debugging.  Disable for performance testing."
+        android:defaultValue="true"
+        />
     <CheckBoxPreference
         android:key="fps_debug"
         android:title="FPS Debugging"