Summing numbers separated by commas in a single cell

I have seen some pretty outlandish code to simply add comma separated numbers in Excel (I am using 2013). What I am looking for should be very simple. I have a list of numbers separated by commas in a single cell (B8)that I simply need to add up to get the total (i.e., 3, 4, 5, 6...the sum would be 18 [shown in cell C8].) Pretty simple, huh? Is there a simple function to do this?  Thanks!