What would be the economic implications of changing US policy to allow Stateside based companies to bring back overseas capital at treasury rate tax costs? I ca

What would be the economic implications of changing US policy to allow Stateside based companies to bring back overseas capital at treasury rate tax costs? I can't really fathom the implications here cause i'm not to privy on the economic theory behind this. Obviously their would be some kind of inflation due to all the money that would flood into the US market, but that would be good for all the corporations with stock, resulting in more money inflooding. But the investment in US based industry would receive a considerable boost, which would be potentially good. I don't really see a downside here, so why does current economic policy dictate such a punishing tax cost to bring overseas cash into the stateside market again?