We have this issue with Caleb ATM.
I found the way to deal with it is to ignore him. Let him hit his head and he will soon learn that it hurts and it's to no avail. A few times I picked him up and put him in his room (didn't shut the door and told him to calm down) because I couldn't bear to hear the thudding on the floorboards.

The cheeky monkey now knows to run to the carpet and do it there because it doesn't hurt. I still ignore it rofl. I must admit I have been thinking of getting the video camera out for future giggles but every time I go to do it the battery is flat!