Lee was added to Atlanta's NLCS roster Wednesday, Bill Shaikin of the Los Angeles Times reports.
The 27-year-old wasn't included on the initial roster for the NLCS, but he'll join the bullpen mix with Huascar Ynoa (shoulder) going down with an injury. Lee made his big-league debut during the final weekend of the regular season, and he spent the rest of the year at Triple-A Gwinnett, where he posted a 1.54 ERA, 0.76 WHIP and 54:6 K:BB across 46.2 innings.