In a quick post on the Laravel News site they point out that the Laravel Homestead virtual machine now has support for PHP 7:

Laravel Homestead just received a new update with support for PHP 7 which is due out this month.

If you are already using the PHP 5.x Homestead box, you can upgrade your installation to PHP 7.0 by cloning the php-7 branch of the laravel/homestead repository into a new folder.

With two other simple steps you can quickly upgrade your box to be running PHP 7 - updating the Homestead.yml configuration and running a vagrant up. You can find out more information about this update in the official documentation.