But I think Lucien doesn't really resemble Lucille as a masculine form, it's closer to Lucius or Lucianus. Thus it doesn't feel right to me as a masculine form.
Some searching on the Internet learned me that there's Lucilian (also spelled as Lucillian) as a name, which would be a much better masculine form for Lucille than Lucien. And apart from Lucilius, Lucillus and Lucilian, I also found Lucilianus. If you see all these various forms, it's a bit odd that they're hardly known and that the French (probably?) never thought of using Lucille as a masculine name as well.