Kenya's government plans to ban bride-price payments, legalise polygamy and consider couples co-habiting for more than six months to be legally married.
The controversial proposals were approved by the cabinet, but will not become law until passed by parliament.
The cabinet said the bill aimed to offer legal protection to all forms of marriages in the country - Christian, Islamic, Hindu, civil and traditional.
It is intended to give women and children protection under the law.
The BBC's Muliro Telewa in the capital, Nairobi, says the decision to stop the age-old custom of bride price is one of the most contentious of the proposals to harmonise the East African nation's marriage laws.
Bride prices are commonly paid by most of Kenya's more than 40 ethnic groups.
Current customary law stipulates that a marriage is not considered legal unless a bride price has been paid, usually in the form of cows.
Even couples married in a religious or civil ceremony will often not be considered bound in the traditional sense by their families unless a payment is made.
Under the new proposals, co-habiting couples in what are known in Kenya as "come-we-stay" relationships will be considered married after a six-month period.
Our correspondent says many couples, among them college students, are in such relationships.
In most of these cases, people live together for convenience and can decide to go their separate ways without any future commitment, he says.
However, in some cases men have been known to walk out if children are born.
If the proposals became law, in rural areas chiefs would have to register "come-we-stay" relationships by issuing marriage certificates and ensuring that in the event of a break-up, maintenance is paid to spouses and any children.
The proposals on legalising polygamy are intended to bring civil law - where a man is only allowed one wife - in line with customary law where some cultures allow for multiple partners.
Despite allowing polygamy, the cabinet says men and women should have equal status within all marriages with regards to property and inheritance.
Gay marriages would not be allowed as they are banned under Kenya's constitution, and the proposals would not affect communities which allow women to marry each other if the older partner is infertile, as these partnerships are usually to do with property inheritance.
Our reporter says the proposals have caused a big stir on social media sites because many people say some of the changes go against traditional and religious values.
As 90% of MPs are men, their past performance on issues of custom and tradition suggests they are likely to oppose sections of the bill, he says.