回複：Can h1b holder take unpaid leave? For how long?

If yes, is there a time limit?

-Yes, don't see any official document limiting the vacation time, but normally one to three months should be fine. Also, the leave without pay should be genuine leaves, not unlawful benching.

See this USCIS website:

http://www.uscis.gov/portal/site/uscis/menuitem.5af9bb95919f35e66f614176543f6d1a/?vgnextoid=a62bec897643f010VgnVCM1000000ecd190aRCRD&vgnextchannel=1847c9ee2f82b010VgnVCM10000045f3d6a1RCRD