diff --git a/wp-includes/cache.php b/wp-includes/cache.php
index 4353687328..ca1dae64e0 100644
--- a/wp-includes/cache.php
+++ b/wp-includes/cache.php
@@ -149,8 +149,9 @@ function wp_cache_set($key, $data, $flag = '', $expire = 0) {
  * @param string|array $groups A group or an array of groups to add
  */
 function wp_cache_add_global_groups( $groups ) {
-	// Default cache doesn't persist so nothing to do here.
-	return;
+	global $wp_object_cache;
+
+	return $wp_object_cache->add_global_groups($groups);
 }
 
 /**
@@ -165,6 +166,20 @@ function wp_cache_add_non_persistent_groups( $groups ) {
 	return;
 }
 
+/**
+ * Reset internal cache keys and structures.  If the cache backend uses global blog or site IDs as part of its cache keys,
+ * this function instructs the backend to reset those keys and perform any cleanup since blog or site IDs have changed since cache init.
+ *
+ * @since 2.6.0
+ *
+ * @param string|array $groups A group or an array of groups to add
+ */
+function wp_cache_reset() {
+	global $wp_object_cache;
+
+	return $wp_object_cache->reset();
+}
+
 /**
  * WordPress Object Cache
  *
@@ -219,6 +234,15 @@ class WP_Object_Cache {
 	 */
 	var $cache_misses = 0;
 
+	/**
+	 * List of global groups
+	 *
+	 * @var array
+	 * @access protected
+	 * @since 3.0.0
+	 */
+	var $global_groups = array();
+
 	/**
 	 * Adds data to the cache if it doesn't already exist.
 	 *
@@ -234,8 +258,8 @@ class WP_Object_Cache {
 	 * @param int $expire When to expire the cache contents
 	 * @return bool False if cache ID and group already exists, true on success
 	 */
-	function add($id, $data, $group = 'default', $expire = '') {
-		if (empty ($group))
+	function add( $id, $data, $group = 'default', $expire = '' ) {
+		if ( empty ($group) )
 			$group = 'default';
 
 		if (false !== $this->get($id, $group))
@@ -244,6 +268,20 @@ class WP_Object_Cache {
 		return $this->set($id, $data, $group, $expire);
 	}
 
+	/**
+	 * Sets the list of global groups.
+	 *
+	 * @since 3.0.0
+	 *
+	 * @param array $groups List of groups that are global.
+	 */
+	function add_global_groups( $groups ) {
+		$groups = (array) $groups;
+
+		$this->global_groups = array_merge($this->global_groups, $groups);
+		$this->global_groups = array_unique($this->global_groups);
+	}
+
 	/**
 	 * Remove the contents of the cache ID in the group
 	 *
@@ -308,10 +346,10 @@ class WP_Object_Cache {
 	 *		contents on success
 	 */
 	function get($id, $group = 'default') {
-		if (empty ($group))
+		if ( empty ($group) )
 			$group = 'default';
 
-		if (isset ($this->cache[$group][$id])) {
+		if ( isset ($this->cache[$group][$id]) ) {
 			$this->cache_hits += 1;
 			if ( is_object($this->cache[$group][$id]) )
 				return wp_clone($this->cache[$group][$id]);
@@ -343,12 +381,25 @@ class WP_Object_Cache {
 		if (empty ($group))
 			$group = 'default';
 
-		if (false === $this->get($id, $group))
+		if ( false === $this->get($id, $group) )
 			return false;
 
 		return $this->set($id, $data, $group, $expire);
 	}
 
+	/**
+	 * Reset keys
+	 *
+	 * @since 3.0.0
+	 */
+	function reset() {
+		// Clear out non-global caches since the blog ID has changed.
+		foreach ( array_keys($this->cache) as $group ) {
+			if ( !in_array($group, $this->global_groups) )
+				unset($this->cache[$group]);
+		}
+	}
+
 	/**
 	 * Sets the data contents into the cache
 	 *
@@ -370,10 +421,10 @@ class WP_Object_Cache {
 	 * @return bool Always returns true
 	 */
 	function set($id, $data, $group = 'default', $expire = '') {
-		if (empty ($group))
+		if ( empty ($group) )
 			$group = 'default';
 
-		if (NULL === $data)
+		if ( NULL === $data )
 			$data = '';
 
 		if ( is_object($data) )
@@ -381,7 +432,7 @@ class WP_Object_Cache {
 
 		$this->cache[$group][$id] = $data;
 
-		if(isset($this->non_existent_objects[$group][$id]))
+		if ( isset($this->non_existent_objects[$group][$id]) )
 			unset ($this->non_existent_objects[$group][$id]);
 
 		return true;
diff --git a/wp-includes/functions.php b/wp-includes/functions.php
index 1ebfcd69ff..6aee150c6e 100644
--- a/wp-includes/functions.php
+++ b/wp-includes/functions.php
@@ -437,6 +437,29 @@ function wp_load_alloptions() {
 	return $alloptions;
 }
 
+function wp_load_core_site_options( $site_id = null ) {
+	global $wpdb, $_wp_using_ext_object_cache;
+
+	if ( !is_multisite() || $_wp_using_ext_object_cache || defined( 'WP_INSTALLING' ) )
+		return;
+
+	if ( empty($site_id) )
+		$site_id = $wpdb->siteid;
+
+	$core_options = array('site_name', 'siteurl', 'active_sitewide_plugins', '_site_transient_timeout_theme_roots', '_site_transient_theme_roots', 'site_admins', 'dashboard_blog');
+
+	$core_options_in = "'" . implode("', '", $core_options) . "'";
+	$options = $wpdb->get_results( $wpdb->prepare("SELECT meta_key, meta_value FROM $wpdb->sitemeta WHERE meta_key IN ($core_options_in) AND site_id = %d", $site_id) );
+
+	foreach ( $options as $option ) {
+		$key = $option->meta_key;
+		$cache_key = "{$site_id}:$key";
+		$option->meta_value = maybe_unserialize( $option->meta_value );
+
+		wp_cache_set( $cache_key, $option->meta_value, 'site-options' );
+	}
+}
+
 /**
  * Update the value of an option that was already added.
  *
@@ -3320,19 +3343,20 @@ function get_site_option( $key, $default = false, $use_cache = true ) {
 	if ( !is_multisite() ) {
 		$value = get_option($key, $default);
 	} else {
-		$cache_key = "{$wpdb->siteid}:$key";
+		$cache_key = "$wpdb->siteid:$key";
+		if ( $use_cache )
+			$value = wp_cache_get($cache_key, 'site-options');
 
-		if ( $use_cache == true && $value = wp_cache_get($cache_key, 'site-options') )
-			return $value;
+		if ( false === $value ) {
+			$value = $wpdb->get_var( $wpdb->prepare("SELECT meta_value FROM $wpdb->sitemeta WHERE meta_key = %s AND site_id = %d", $key, $wpdb->siteid) );
 
-		$value = $wpdb->get_var( $wpdb->prepare("SELECT meta_value FROM $wpdb->sitemeta WHERE meta_key = %s AND site_id = %d", $key, $wpdb->siteid) );
+			if ( is_null($value) )
+				$value = $default;
 
-		if ( is_null($value) )
-			$value = $default;
+			$value = maybe_unserialize( $value );
 
-		$value = maybe_unserialize( $value );
-
-		wp_cache_set( $cache_key, $value, 'site-options' );
+			wp_cache_set( $cache_key, $value, 'site-options' );
+		}
 	}
 
  	return apply_filters( 'site_option_' . $key, $value );
diff --git a/wp-includes/load.php b/wp-includes/load.php
index fb5a249120..0640fde78c 100644
--- a/wp-includes/load.php
+++ b/wp-includes/load.php
@@ -318,7 +318,8 @@ function wp_set_wpdb_vars() {
  * @since 3.0.0
  */
 function wp_start_object_cache() {
-	if ( ! function_exists( 'wp_cache_init' ) ) {
+	$first_init = false;
+ 	if ( ! function_exists( 'wp_cache_init' ) ) {
 		global $_wp_using_ext_object_cache;
 		if ( file_exists( WP_CONTENT_DIR . '/object-cache.php' ) ) {
 			require_once ( WP_CONTENT_DIR . '/object-cache.php' );
@@ -327,9 +328,17 @@ function wp_start_object_cache() {
 			require_once ( ABSPATH . WPINC . '/cache.php' );
 			$_wp_using_ext_object_cache = false;
 		}
+		$first_init = true;
 	}
 
-	wp_cache_init();
+	// If cache supports reset, reset instead of init if already initialized.
+	// Reset signals to the cache that global IDs have changed and it may need to update keys
+	// and cleanup caches.
+	if ( !$first_init && function_exists('wp_cache_reset') )
+		wp_cache_reset();
+	else
+		wp_cache_init();
+
 	if ( function_exists( 'wp_cache_add_global_groups' ) ) {
 		wp_cache_add_global_groups( array( 'users', 'userlogins', 'usermeta', 'site-transient', 'site-options', 'site-lookup', 'blog-lookup', 'blog-details', 'rss' ) );
 		wp_cache_add_non_persistent_groups( array( 'comment', 'counts', 'plugins' ) );
diff --git a/wp-includes/ms-load.php b/wp-includes/ms-load.php
index bd042a076b..77ba711b28 100644
--- a/wp-includes/ms-load.php
+++ b/wp-includes/ms-load.php
@@ -75,11 +75,14 @@ function ms_site_check() {
  */
 function get_current_site_name( $current_site ) {
 	global $wpdb;
-	$current_site->site_name = wp_cache_get( $current_site->id . ':current_site_name', "site-options" );
+	$current_site->site_name = wp_cache_get( $current_site->id . ':current_site_name', 'site-options' );
 	if ( ! $current_site->site_name ) {
-		$current_site->site_name = $wpdb->get_var( $wpdb->prepare( "SELECT meta_value FROM $wpdb->sitemeta WHERE site_id = %d AND meta_key = 'site_name'", $current_site->id ) );
-		if ( ! $current_site->site_name )
-			$current_site->site_name = ucfirst( $current_site->domain );
+		$current_site->site_name = wp_cache_get( $current_site->id . ':site_name', 'site-options' );
+		if ( ! $current_site->site_name ) {
+			$current_site->site_name = $wpdb->get_var( $wpdb->prepare( "SELECT meta_value FROM $wpdb->sitemeta WHERE site_id = %d AND meta_key = 'site_name'", $current_site->id ) );
+			if ( ! $current_site->site_name )
+				$current_site->site_name = ucfirst( $current_site->domain );
+		}
 		wp_cache_set( $current_site->id . ':current_site_name', $current_site->site_name, 'site-options' );
 	}
 	return $current_site;
@@ -107,6 +110,8 @@ function wpmu_current_site() {
 		else
 			$current_site->cookie_domain = $current_site->domain;
 
+		wp_load_core_site_options($current_site->id);
+
 		return $current_site;
 	}
 
@@ -116,6 +121,7 @@ function wpmu_current_site() {
 
 	$sites = $wpdb->get_results( "SELECT * FROM $wpdb->site" ); // usually only one site
 	if ( 1 == count( $sites ) ) {
+		wp_load_core_site_options($current_site->id);
 		$current_site = $sites[0];
 		$path = $current_site->path;
 		$current_site->blog_id = $wpdb->get_var( $wpdb->prepare( "SELECT blog_id FROM $wpdb->blogs WHERE domain = %s AND path = %s", $current_site->domain, $current_site->path ) );