--- a/services/fxaccounts/FxAccounts.jsm
+++ b/services/fxaccounts/FxAccounts.jsm
@@ -494,42 +494,58 @@ FxAccountsInternal.prototype = {
       log.debug("Polling aborted; Another user signing in");
       clearTimeout(this.currentTimer);
       this.currentTimer = 0;
     }
     this.currentAccountState.abort();
     this.currentAccountState = new AccountState(this);
   },
 
-  signOut: function signOut() {
+  signOut: function signOut(localOnly) {
     let currentState = this.currentAccountState;
-    let fxAccountsClient = this.fxAccountsClient;
     let sessionToken;
     return currentState.getUserAccountData().then(data => {
       // Save the session token for use in the call to signOut below.
       sessionToken = data && data.sessionToken;
-      this.abortExistingFlow();
-      this.currentAccountState.signedInUser = null; // clear in-memory cache
-      return this.signedInUserStorage.set(null);
+      return this._signOutLocal();
     }).then(() => {
-      // Wrap this in a promise so *any* errors in signOut won't
-      // block the local sign out. This is *not* returned.
-      Promise.resolve().then(() => {
-        // This can happen in the background and shouldn't block
-        // the user from signing out. The server must tolerate
-        // clients just disappearing, so this call should be best effort.
-        return fxAccountsClient.signOut(sessionToken);
-      }).then(null, err => {
-        log.error("Error during remote sign out of Firefox Accounts: " + err);
-      });
+      // FxAccountsManager calls here, then does its own call
+      // to FxAccountsClient.signOut().
+      if (!localOnly) {
+        // Wrap this in a promise so *any* errors in signOut won't
+        // block the local sign out. This is *not* returned.
+        Promise.resolve().then(() => {
+          // This can happen in the background and shouldn't block
+          // the user from signing out. The server must tolerate
+          // clients just disappearing, so this call should be best effort.
+          return this._signOutServer(sessionToken);
+        }).then(null, err => {
+          log.error("Error during remote sign out of Firefox Accounts: " + err);
+        });
+      }
+    }).then(() => {
       this.notifyObservers(ONLOGOUT_NOTIFICATION);
     });
   },
 
   /**
+   * This function should be called in conjunction with a server-side
+   * signOut via FxAccountsClient.
+   */
+  _signOutLocal: function signOutLocal() {
+    this.abortExistingFlow();
+    this.currentAccountState.signedInUser = null; // clear in-memory cache
+    return this.signedInUserStorage.set(null);
+  },
+
+  _signOutServer: function signOutServer(sessionToken) {
+    return this.fxAccountsClient.signOut(sessionToken);
+  },
+
+  /**
    * Fetch encryption keys for the signed-in-user from the FxA API server.
    *
    * Not for user consumption.  Exists to cause the keys to be fetch.
    *
    * Returns user data so that it can be chained with other methods.
    *
    * @return Promise
    *        The promise resolves to the credentials object of the signed-in user:

--- a/services/fxaccounts/FxAccountsManager.jsm
+++ b/services/fxaccounts/FxAccountsManager.jsm
@@ -158,17 +158,17 @@ this.FxAccountsManager = {
     }
 
     // We clear the local session cache as soon as we get the onlogout
     // notification triggered within FxAccounts.signOut, so we save the
     // session token value to be able to remove the remote server session
     // in case that we have network connection.
     let sessionToken = this._activeSession.sessionToken;
 
-    return this._fxAccounts.signOut(sessionToken).then(
+    return this._fxAccounts.signOut(true).then(
       () => {
         // At this point the local session should already be removed.
 
         // The client can create new sessions up to the limit (100?).
         // Orphaned tokens on the server will eventually be garbage collected.
         if (Services.io.offline) {
           return Promise.resolve();
         }