On/Off status - if a time falls between two times and status hasn't changed, same status

Ha, I didn't know how to title this one.

I have a bunch of on/off status data, like this (full timestamp with date is in one column, on/off status in another column):

8/11/2014 3:44:38 PM On
8/11/2014 10:01:06 PM Off
8/12/2014 2:11:49 AM On
8/12/2014 2:22:42 AM Off

I have another set of data in 15-minute increments, and I want to correlate the on/off status data to it; for example, for these few 15-minute increments the status data would be:

8/12/2014 1:45:00 AM Off
8/12/2014 2:00:00 AM Off
8/12/2014 2:15:00 AM On
8/12/2014 2:30:00 AM Off

Hopefully that demonstrates what I'm after - is there an Excel formulaic way to do this? Thanks!

That works well enough, thank you!