McDonald's Corp's turnaround is showing signs of gaining steam - helped by all-day breakfast, value deals and lower commodity prices - even as labor costs and other headwinds linger.

The fast-food chain posted a 6.2 percent gain in same-store sales last quarter, the best performance in four years, and earnings topped analysts' estimates.

The results showed Chief Executive Officer Steve Easterbrook's plan to revive the world's largest restaurant chain is gathering momentum. Since taking the helm more than a year ago, he has revamped drive-thru ordering, tweaked kitchen operations and slimmed down the menu. The company also has reignited sales in the United States with all-day breakfast and McPick two-for-$2 and two-for-$5 deals.