Two Scales X-Axis- How?

So I have two sets of data- one from a pre-trial (measured over months) and one from a trial (measured over days). I would like to plot both on the same line chart. Both sets of data have the same y-axis scale. However, I would like to have the scale for the x-axis (time) split into two. I would like the pre-trial data to be in months, and then the trial data follow after in days. Is there anyway to split the x-axis into two different scales?