Landlord wants to cancel lease agreement

My landlord has told me he wants to move into the apartment I'm renting from him as soon as he sells his house. This situation wasn't foreseen in the lease agreement. He has said he'll give me 3-4 months notice but I wonder if I have any rights in this situation? For example, the right to move out sooner with no penalty payment; the right to refuse to leave till the lease expires; the right to ask for him to pay removal costs, etc. Any ideas?