Is the Baxalta exchange reported as a long term capital gain based on the holding period of the Baxter stock or short term based on the Baxalta holding period?

I acquired Baxalta as a result of owning Baxter shares.  When reporting the gain from the Baxalta Shire exchange should this be a long term capital gain based on the holding period of the Baxter stock or a short term capital gain based on the holding period of the Baxalta stock?  I did not purchase Baxalta but received it as a result of the spinoff.  The only shares I purchased were Baxter many years ago.

Thanks for your help.