How to normalize output of $\tt scipy.signal.correlate$
When you say normalized cross-correlation I guess you mean the Pearson correlation. 
Anyways you just divide the cross correlation by the multiplication of the std(standard deviation) of both signal, or more conveniently:
$ \rho_{xy}  =\frac{&lt;x,y&gt;}{\sigma_x\sigma_y}$

and in code:

x1 = x1/x1.std()
x2 = x2/x2.std() and then as you did it