What is the procedure to make a shift from H1b visa to L1 visa while staying in USA?

I am on H1b right now staying in USA. I have to shift from H1b visa to L1 visa. What is the procedure? Do i have to go to India for Stamping? How many days it will take?

2 options:

  1. File L1 and COS while staying inside US. Once approved you will be on L1 and you can get L1 stamped next time you travel outside of US.

  2. File L1 without COS, or COS is applied but denied. Go for L1 stamping and return on stamped L1 visa to work on that visa.