Python/Matplotlib - Adjusting the spacing between the edge of the plot and the x-axis

How can I adjust the amount of space between the x-axis and the edge of the plot window? My x-axis labels are oriented vertically and they are running off of the edge of the window that Matplotlib draws.

Here's some example code:

import matplotlib.pyplot as plt
x=[1,2,3,4,5]
y=[1,2,3,4,5]
plt.plot(x,y)
plt.xticks(rotation='vertical')
plt.show()