Designed to reward innovation, patent protection often leads to high drug prices that make life-saving medicines unaffordable for patients. This tension further increases patent infringement and invalidation to reduce prices, particularly in developing countries. The situation is serious for treatments that require multiple drugs owned by different firms with numerous patents, notably for HIV. I study the impact of the first joint licensing platform for drug bundling, the Medicines Patent Pool, on global drug diffusion and innovation. The pool allows generic firms worldwide to license drug bundles cheaply and conveniently for sales in a set of developing countries. I construct a novel dataset from licensing contracts, public procurement, clinical trials, and drug approvals. Using difference-in-differences methods, I find robust evidence that the pool leads to a substantial increase in the generic supply of drugs purchased. In addition, branded-drug makers and other entities, such as public institutions, respond to the pool by increasing the number of new clinical trials. The R&D input increase is accompanied by increases in generic drug product approvals. Finally, I estimate a structural model to quantify welfare gains and simulate counterfactuals. The benefit to consumers and firms far exceeds the associated costs.