Librax and breastfeeding are not considered compatible.
Librax, a combination drug of chlordiazepoxide and clidinium, should not be taken by any female in the childbearing age unless effective contraception is used. (Since we all know that contraception is not 100% effective, you should probably just avoid it at this stage of life!)
The potential danger of Librax while breastfeeding, of course, is a high risk of injury to your baby.
This is a Very Unsafe Drug
As you may know, the FDA has a grading system for each drug which reflects its safety. It ranks drugs from A, where medical studies show no evidence for danger to the baby or the mother, to B, C, D and X, where the medical evidence indicates that the risk to the baby outweighs any benefit to mom. Chlordiazepoxide (half of the combination drug of Librax) is ranked a D.
For this reason, completely avoid using Librax while breastfeeding. Ask your doctor for other options.