How can I display previous monthname including the year?

I have the following sql statement:

SELECT Cast(datename(month, dateadd(mm, -1, getdate())) as varchar(15)) + '-' + Cast((DATEPART(YYYY,GETDATE())) As CHAR(4))

The result displays as July-2014 which is correct for previous month...

But on next year January-2015 it will display December-2015.

Is it possible to have the date shown as December-2014?

I appreciate any help.

Thanks in advance.