There are signs that Warren Buffett's buying spree that began earlier this year is winding down. The legendary investor didn't buy any new stocks for Berkshire Hathaway's (BRK.A 0.55%) (BRK.B 0.50%) portfolio in the second quarter, although he did add to a few positions.

Several stocks held by Berkshire remain attractive. Here are three no-brainer Buffett stocks to buy in September.

1. Apple

Apple (AAPL -1.00%) ranks by far as the largest holding in Berkshire's portfolio. Buffett couldn't resist scooping up even more shares of the technology giant in Q2. Apple stock isn't as attractively valued as it was in June, but it's still a smart pick.

The new iPhone 14 will be launched on Sept. 7, 2022. Apple's rollouts of new iPhone versions typically fuel higher sales during the latter part of each year. Although no major changes are expected with iPhone 14, the company seems likely to benefit from increased momentum as a result of its launch.

There are other growth drivers for Apple's iPhone ecosystem that are more important for the company's long-term prospects, though. In particular, increasing 5G adoption should serve as a significant tailwind. Apple CEO Tim Cook correctly noted in the company's Q2 conference call that global 5G penetration remains low.

Cook didn't talk about Apple's augmented reality (AR) plans in the Q2 call. However, the company could introduce an AR/mixed reality (MR) headset in early 2023. Analyst Ming-Chi Kuo believes this device could be the biggest product for Apple since the iPhone.

2. Chevron

It's no secret that Buffett has become a big fan of oil stocks. Berkshire could be gearing up to buy a much larger stake in Occidental Petroleum. However, Chevron (CVX -0.49%) is arguably the best Buffett stock in the energy sector.

While Chevron's shares have soared so far this year, the stock remains attractively valued with a forward earnings multiple of around nine times. Income investors will also like the oil and gas giant's dividend yield of over 3.6%.

Over the short term, Chevron could benefit from another uptick in fuel prices. OPEC has already signaled that it's open to reducing oil production, a move that would almost certainly cause prices to rise. The European Union will also impose a partial ban on Russian crude oil imports in December.

Chevron has a strong financial position that it's using to, in CFO Pierre Breber's words, "invest and grow both traditional and new energy." The sizzling stock performance might cool off over time. Over the next year or so, though, the stock could continue its winning ways.

3. Markel

Buffett initiated a brand-new position in Markel (MKL -0.20%) in the first quarter and bought even more shares in Q2. This wasn't surprising whatsoever, considering that Markel is basically a "baby Berkshire."

Markel ranks as a leader in the specialty insurance market. The company's underwriting expertise enables it to consistently generate profits. Its reputation allows it to attract new customers and hold onto existing ones.

The stock's performance over the next several months will likely depend largely on how the overall market does. That's because Markel, like Berkshire, invests heavily in other publicly traded businesses. But there are some reasons to believe that a new bull market could be emerging. If so, Markel's shares could surge higher.

Long-term investors have to love what Markel co-CEO Tom Gayner said in the company's recent Q2 conference call, "We think about years and decades and generations rather than quarters." That perspective sounds a lot like Buffett himself. With its exceptional management team and strong underlying business, Markel is the kind of stock you can buy in any month and hold for years.