I am sorry but at the moment there are no generic versions. The patent for olmesartan does not come off the brand for another couple of years at least.
Olmesartan is an Angiotensin II receptor blocker. There are generic versions of some of the other drugs in the same family (candesarten and losarten) however you would need to check with your doctor that these were suitable for you. You would also have to take a separate hydrochlorthiazide tablet too. As Benicar HCT is a combination product.