Johnson Controls' shares were up 5.3 percent at $37.40 in premarket trading on Monday. Tyco's shares were up 10 percent at $33.65.
The businesses of Johnson Controls and Tyco will be combined under Tyco International Plc, which will be renamed Johnson Controls Plc, after the deal closes.
The combined company would be domiciled in low-tax Ireland.
The deal will result in at least $500 million in savings in the first three years, and create at least $150 million in annual tax savings, the companies said.
The new company will be headed by Johnson Controls Chief Executive Alex Molinaroli and will continue to trade under the "JCI" ticker on the New York Stock Exchange.
Johnson Controls' shareholders will own about 56 percent of the combined company and receive a cash consideration of about $3.9 billion, upon closure of the deal.
Centerview Partners and Barclays were financial advisers to Johnson Controls, while Lazard and Goldman Sachs advised Tyco.