Border's Unused Idle and Lying Dormant Inventory Transfer Act or the BUILD IT Act This bill requires the federal government to transfer, upon request, materials associated with the construction of a barrier along the U.S.-Mexico border to the governments of the states along that border (i.e., Arizona, California, New Mexico, and Texas). The transferred materials must be used to construct, repair, or reinforce a barrier along the U.S.-Mexico border. The federal government must cancel any existing contracts relating to the maintenance and security of the materials if the cancellation is necessary to transfer the materials.