They can certainly accommodate a lot of people. They have over 100,000 air conditioned tents at Mecca which can hold over 3 million people:
http://www.bricoleurbanism.org/beautiful-urban-moments/mina-...
https://en.wikipedia.org/wiki/Mina,_Saudi_Arabia
Despite the facility to do so, they take in no refugees. https://www.amnesty.org/en/latest/news/2014/12/facts-figures...