Australia's race hate laws have lost credibility, Prime Minister Malcolm Turnbull says, and fixing them requires the removal of legal prohibitions on people's right to "offend, insult or humiliate", while making it illegal to "harass".

In a move that has delighted the right of the Coalition and dismayed MPs who hold marginal seats or represent ethnic communities, Mr Turnbull and Attorney-General George Brandis unveiled changes to the language of section 18C of the Racial Discrimination Act.

Changes to how the Human Rights Commission handles complaints under the Racial Discrimination Act are also on the way.

The Commission president, currently Gillian Triggs, will have to rule early on whether a complaint has merit and should proceed; complaints will have to be lodged within six months of an incident, and then dealt with more quickly - within 12 months.