Sync up time for two cameras

I took some photos with two cameras and then realize the time were not in sync. Are there any free tools that I can simply add X min to the time stamp of a set of files?

What do you use for post work? Lightroom can do that.

Lightroom will only either set all pictures to a specific time or adjust the hour up or down. I struggle with that too, I always forget to synchronize the camera time on my second camera when my wife uses it.

Makes geo-tagging a little more difficult

I use lightroom 5, how do you adjust/change file timestamp there?

Do you mean date/time as within the EXIF or do you just mean the file date/time parameters?

You can sync the bodies with EOS Utility so they have the sames times in them, then the resulting shots can be laid out in chronological sequence within Lightroom...

But then you have to do it in advance. Too late for that in this case.

I always set the cameras that support it to set their time from the GPS. Then you never get this issue.