diff --git a/app/src/main/java/org/mozilla/fenix/components/FxaServer.kt b/app/src/main/java/org/mozilla/fenix/components/FxaServer.kt
index 78d76342b..5967bac44 100644
--- a/app/src/main/java/org/mozilla/fenix/components/FxaServer.kt
+++ b/app/src/main/java/org/mozilla/fenix/components/FxaServer.kt
@@ -7,6 +7,7 @@ import android.content.Context
 import mozilla.components.service.fxa.ServerConfig
 import mozilla.components.service.fxa.ServerConfig.Server
 import org.mozilla.fenix.FeatureFlags
+import org.mozilla.fenix.ext.settings
 
 /**
  * Utility to configure Firefox Account servers.
@@ -24,6 +25,11 @@ object FxaServer {
     }
 
     fun config(context: Context): ServerConfig {
-        return ServerConfig(Server.RELEASE, CLIENT_ID, redirectUrl(context))
+        val serverOverride = context.settings().overrideFxAServer
+        val tokenServerOverride = context.settings().overrideSyncTokenServer.ifEmpty { null }
+        if (serverOverride.isEmpty()) {
+            return ServerConfig(Server.RELEASE, CLIENT_ID, redirectUrl(context), tokenServerOverride)
+        }
+        return ServerConfig(serverOverride, CLIENT_ID, redirectUrl(context), tokenServerOverride)
     }
 }
diff --git a/app/src/main/java/org/mozilla/fenix/settings/SettingsFragment.kt b/app/src/main/java/org/mozilla/fenix/settings/SettingsFragment.kt
index f7e529aa1..8aae91345 100644
--- a/app/src/main/java/org/mozilla/fenix/settings/SettingsFragment.kt
+++ b/app/src/main/java/org/mozilla/fenix/settings/SettingsFragment.kt
@@ -10,6 +10,8 @@ import android.content.Intent
 import android.net.Uri
 import android.os.Bundle
 import androidx.appcompat.content.res.AppCompatResources
+import android.os.Handler
+import android.widget.Toast
 import androidx.lifecycle.lifecycleScope
 import androidx.navigation.NavDirections
 import androidx.navigation.findNavController
@@ -45,6 +47,7 @@ import org.mozilla.fenix.ext.settings
 import org.mozilla.fenix.ext.showToolbar
 import org.mozilla.fenix.settings.account.AccountAuthErrorPreference
 import org.mozilla.fenix.settings.account.AccountPreference
+import kotlin.system.exitProcess
 
 @Suppress("LargeClass", "TooManyFunctions")
 class SettingsFragment : PreferenceFragmentCompat() {
@@ -300,6 +303,29 @@ class SettingsFragment : PreferenceFragmentCompat() {
             requireComponents.core.engine.settings.remoteDebuggingEnabled = newValue
             true
         }
+
+        val preferenceFxAOverride =
+            findPreference<Preference>(getPreferenceKey(R.string.pref_key_override_fxa_server))
+        val preferenceSyncOverride =
+            findPreference<Preference>(getPreferenceKey(R.string.pref_key_override_sync_tokenserver))
+
+        val syncFxAOverrideUpdater = object : StringSharedPreferenceUpdater() {
+            override fun onPreferenceChange(preference: Preference, newValue: Any?): Boolean {
+                return super.onPreferenceChange(preference, newValue).also {
+                    updateFxASyncOverrideMenu()
+                    Toast.makeText(
+                        context,
+                        getString(R.string.toast_override_fxa_sync_server_done),
+                        Toast.LENGTH_LONG
+                    ).show()
+                    Handler().postDelayed({
+                        exitProcess(0)
+                    }, FXA_SYNC_OVERRIDE_EXIT_DELAY)
+                }
+            }
+        }
+        preferenceFxAOverride?.onPreferenceChangeListener = syncFxAOverrideUpdater
+        preferenceSyncOverride?.onPreferenceChangeListener = syncFxAOverrideUpdater
     }
 
     private fun navigateFromSettings(directions: NavDirections) {
@@ -343,6 +369,8 @@ class SettingsFragment : PreferenceFragmentCompat() {
         val accountManager = requireComponents.backgroundServices.accountManager
         val account = accountManager.authenticatedAccount()
 
+        updateFxASyncOverrideMenu()
+
         // Signed-in, no problems.
         if (account != null && !accountManager.accountNeedsReauth()) {
             preferenceSignIn?.isVisible = false
@@ -388,7 +416,31 @@ class SettingsFragment : PreferenceFragmentCompat() {
         }
     }
 
+    private fun updateFxASyncOverrideMenu() {
+        val preferenceFxAOverride =
+            findPreference<Preference>(getPreferenceKey(R.string.pref_key_override_fxa_server))
+        val preferenceSyncOverride =
+            findPreference<Preference>(getPreferenceKey(R.string.pref_key_override_sync_tokenserver))
+        val settings = requireContext().settings()
+        val show = settings.overrideFxAServer.isNotEmpty() ||
+                settings.overrideSyncTokenServer.isNotEmpty() ||
+                settings.showSecretDebugMenuThisSession
+        // Only enable changes to these prefs when the user isn't connected to an account.
+        val enabled = requireComponents.backgroundServices.accountManager.authenticatedAccount() == null
+        preferenceFxAOverride?.apply {
+            isVisible = show
+            isEnabled = enabled
+            summary = settings.overrideFxAServer.ifEmpty { null }
+        }
+        preferenceSyncOverride?.apply {
+            isVisible = show
+            isEnabled = enabled
+            summary = settings.overrideSyncTokenServer.ifEmpty { null }
+        }
+    }
+
     companion object {
         private const val SCROLL_INDICATOR_DELAY = 10L
+        private const val FXA_SYNC_OVERRIDE_EXIT_DELAY = 2000L
     }
 }
diff --git a/app/src/main/java/org/mozilla/fenix/settings/about/AboutFragment.kt b/app/src/main/java/org/mozilla/fenix/settings/about/AboutFragment.kt
index 66cda3490..e96d6be35 100644
--- a/app/src/main/java/org/mozilla/fenix/settings/about/AboutFragment.kt
+++ b/app/src/main/java/org/mozilla/fenix/settings/about/AboutFragment.kt
@@ -10,6 +10,7 @@ import android.os.Bundle
 import android.view.LayoutInflater
 import android.view.View
 import android.view.ViewGroup
+import android.widget.Toast
 import androidx.core.content.pm.PackageInfoCompat
 import androidx.fragment.app.Fragment
 import androidx.recyclerview.widget.DividerItemDecoration
@@ -20,6 +21,7 @@ import org.mozilla.fenix.BuildConfig
 import org.mozilla.fenix.R
 import org.mozilla.fenix.components.metrics.Event
 import org.mozilla.fenix.ext.requireComponents
+import org.mozilla.fenix.ext.settings
 import org.mozilla.fenix.lib.Do
 import org.mozilla.fenix.settings.SupportUtils
 import org.mozilla.fenix.settings.about.AboutItemType.LICENSING_INFO
@@ -36,6 +38,8 @@ import org.mozilla.geckoview.BuildConfig as GeckoViewBuildConfig
 class AboutFragment : Fragment(), AboutPageListener {
     private lateinit var appName: String
     private val aboutPageAdapter: AboutPageAdapter = AboutPageAdapter(this)
+    private var secretDebugMenuClicks = 0
+    private var lastDebugMenuToast: Toast? = null
 
     override fun onCreateView(
         inflater: LayoutInflater,
@@ -49,6 +53,11 @@ class AboutFragment : Fragment(), AboutPageListener {
         return rootView
     }
 
+    override fun onResume() {
+        super.onResume()
+        secretDebugMenuClicks = 0
+    }
+
     @ExperimentalCoroutinesApi
     override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
         super.onViewCreated(view, savedInstanceState)
@@ -63,6 +72,34 @@ class AboutFragment : Fragment(), AboutPageListener {
             )
         }
 
+        // 5 taps on the logo activate the "secret" debug menu.
+        wordmark.setOnClickListener {
+            // Because the user will mostly likely tap the logo in rapid succession,
+            // we ensure only 1 toast is shown at any given time.
+            lastDebugMenuToast?.let { toast -> toast.cancel() }
+            secretDebugMenuClicks += 1
+            when (secretDebugMenuClicks) {
+                in 2 until SECRET_DEBUG_MENU_CLICKS -> {
+                    val clicksLeft = SECRET_DEBUG_MENU_CLICKS - secretDebugMenuClicks
+                    val toast = Toast.makeText(
+                        context,
+                        getString(R.string.about_debug_menu_toast_progress, clicksLeft),
+                        Toast.LENGTH_SHORT
+                    )
+                    toast.show()
+                    lastDebugMenuToast = toast
+                }
+                SECRET_DEBUG_MENU_CLICKS -> {
+                    Toast.makeText(
+                        context,
+                        getString(R.string.about_debug_menu_toast_done),
+                        Toast.LENGTH_LONG
+                    ).show()
+                    requireContext().settings().showSecretDebugMenuThisSession = true
+                }
+            }
+        }
+
         populateAboutHeader()
         aboutPageAdapter.submitList(populateAboutList())
     }
@@ -183,5 +220,7 @@ class AboutFragment : Fragment(), AboutPageListener {
 
     companion object {
         private const val ABOUT_LICENSE_URL = "about:license"
+        // Number of clicks on the app logo to enable the "secret" debug menu.
+        private const val SECRET_DEBUG_MENU_CLICKS = 5
     }
 }
diff --git a/app/src/main/java/org/mozilla/fenix/utils/Settings.kt b/app/src/main/java/org/mozilla/fenix/utils/Settings.kt
index 0510f67d3..5b4c5f4cf 100644
--- a/app/src/main/java/org/mozilla/fenix/utils/Settings.kt
+++ b/app/src/main/java/org/mozilla/fenix/utils/Settings.kt
@@ -187,6 +187,8 @@ class Settings private constructor(
                 (trackingProtectionOnboardingCount < trackingProtectionOnboardingMaximumCount &&
                 !trackingProtectionOnboardingShownThisSession)
 
+    var showSecretDebugMenuThisSession = false
+
     val shouldShowSecurityPinWarningSync: Boolean
         get() = loginsSecureWarningSyncCount < showLoginsSecureWarningSyncMaxCount
 
@@ -597,4 +599,14 @@ class Settings private constructor(
         appContext.getPreferenceKey(R.string.pref_key_open_links_in_external_app),
         default = false
     )
+
+    var overrideFxAServer by stringPreference(
+        appContext.getPreferenceKey(R.string.pref_key_override_fxa_server),
+        default = ""
+    )
+
+    var overrideSyncTokenServer by stringPreference(
+        appContext.getPreferenceKey(R.string.pref_key_override_sync_tokenserver),
+        default = ""
+    )
 }
diff --git a/app/src/main/res/values/preference_keys.xml b/app/src/main/res/values/preference_keys.xml
index 1b622472f..fd44fb5bf 100644
--- a/app/src/main/res/values/preference_keys.xml
+++ b/app/src/main/res/values/preference_keys.xml
@@ -38,6 +38,8 @@
     <string name="pref_key_account" translatable="false">pref_key_account</string>
     <string name="pref_key_sign_in" translatable="false">pref_key_sign_in</string>
     <string name="pref_key_account_auth_error" translatable="false">pref_key_account_auth_error</string>
+    <string name="pref_key_override_fxa_server" translatable="false">pref_key_override_fxa_server</string>
+    <string name="pref_key_override_sync_tokenserver" translatable="false">pref_key_override_sync_tokenserver</string>
     <string name="pref_key_private_mode" translatable="false">pref_key_private_mode</string>
     <string name="pref_key_customize" translatable="false">pref_key_customize</string>
     <string name="pref_key_toolbar" translatable="false">pref_key_toolbar</string>
diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
index 7b1111b18..9cffd5513 100644
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -202,6 +202,12 @@
     <string name="preferences_add_private_browsing_shortcut">Add private browsing shortcut</string>
     <!-- Preference for accessibility -->
     <string name="preferences_accessibility">Accessibility</string>
+    <!-- Preference to override the Firefox Account server -->
+    <string name="preferences_override_fxa_server">Custom Firefox Account server</string>
+    <!-- Preference to override the Sync token server -->
+    <string name="preferences_override_sync_tokenserver">Custom Sync server</string>
+    <!-- Toast shown after updating the FxA/Sync server override preferences -->
+    <string name="toast_override_fxa_sync_server_done">Firefox Account/Sync server modified. Quitting the application to apply changes…</string>
     <!-- Preference category for account information -->
     <string name="preferences_category_account">Account</string>
     <!-- Preference shown on banner to sign into account -->
@@ -1062,6 +1068,10 @@
     <string name="about_licensing_information">Licensing information</string>
     <!-- About page link text to open a screen with libraries that are used -->
     <string name="about_other_open_source_libraries">Libraries that we use</string>
+    <!-- Toast shown to the user when they are activating the secret dev menu
+        The first parameter is number of long clicks left to enable the menu -->
+    <string name="about_debug_menu_toast_progress">Debug menu: %1$d click(s) left to enable</string>
+    <string name="about_debug_menu_toast_done">Debug menu enabled</string>
 
     <!-- Content description of the tab counter toolbar button when one tab is open -->
     <string name="tab_counter_content_description_one_tab">1 tab</string>
diff --git a/app/src/main/res/xml/preferences.xml b/app/src/main/res/xml/preferences.xml
index 283349827..2f727bef3 100644
--- a/app/src/main/res/xml/preferences.xml
+++ b/app/src/main/res/xml/preferences.xml
@@ -29,6 +29,20 @@
             android:key="@string/pref_key_account_auth_error"/>
     </androidx.preference.PreferenceCategory>
 
+    <androidx.preference.EditTextPreference
+        android:key="@string/pref_key_override_fxa_server"
+        android:title="@string/preferences_override_fxa_server"
+        android:inputType="textUri"
+        app:iconSpaceReserved="false"
+        app:isPreferenceVisible="false"/>
+
+    <androidx.preference.EditTextPreference
+        android:key="@string/pref_key_override_sync_tokenserver"
+        android:title="@string/preferences_override_sync_tokenserver"
+        android:inputType="textUri"
+        app:iconSpaceReserved="false"
+        app:isPreferenceVisible="false"/>
+
     <androidx.preference.PreferenceCategory
         android:title="@string/preferences_category_general"
         app:iconSpaceReserved="false">