Use the Logo from BeaverBiulder's settings for the WordPress login screen.

bbLogin.php

<?php
/**
 * Custom Login
 * Pulls the logo from the BeverBuilder's customizer settings.
 */
function bbLogo_login_logo() {

    $LogoImage = get_theme_mod( 'fl-logo-image-retina');
    if ( !$LogoImage ) {
        $LogoImage = get_theme_mod( 'fl-logo-image');
    }

    if ( $LogoImage ) {
        ?>
        <style type="text/css">
            body.login div#login h1 a {
                background-image: url(<?php echo $LogoImage; ?>);
                padding-bottom: 0px;
                margin-bottom: 0px;
                background-size: 200px;
                width: auto;
            }
        </style>
    <?php } ?>
<?php }
add_action( 'login_enqueue_scripts', 'bbLogo_login_logo' );
function bbLogo_login_logo_url() {
    return home_url();
}
add_filter( 'login_headerurl', 'bbLogo_login_logo_url' );
function bbLogo_login_logo_url_title() {
    return get_bloginfo('name');
}
add_filter( 'login_headertitle', 'bbLogo_login_logo_url_title' );

The one downside to this code is that I have the background-size hard coded. That should be updated to be more dynamic in the future.