It is need-based. You will have to fill in forms to apply and they will assess your individual needs accordingly. Most of the time, I'm thinking about 10% of your parents' income as the cost for tuition fee? 100% if you're really really poor. But one thing is for sure, they will make sure that you can afford to go there if you receive their offer. Then again, receiving offers from Yale, Princeton, Harvard, or MIT is better then receiving a scholarship
Some universities offer scholarships for intls too (stanford, upenn) but they'll place you in an extremely competitive pool of applicants. THAT, is merit-based and this is going to affect your place in the uni. My advice for you now is to take a pre U course (a levels, IB, or stpm etc) and then apply to universities. Note that obtaining places from top universities will not exactly increase your chances for scholarships because i got into cambridge and got rejected by plenty of organisations as well. just try your luck and do not be afraid to fall
Have you tried applying for scholarships as a post SPM student? I know bnm and sime darby has that. Btw, you need to know the exact "fit" they're looking when making your applications, that's a trick I've learnt.