RIYADH, Saudi Arabia—President Donald Trump, who has frequently aired views hostile to Islam, is traveling to the religion’s cradle in a trip intended to shore up his ties with the Muslim world.

Saudi Arabia is rolling out the red carpet for Mr. Trump, who arrived in Riyadh Saturday for a two-day visit that marks the start of his first foreign trip as president. The capital’s wide avenues are lined with Saudi and American flags and billboards featuring King Salman and Mr. Trump, and a ubiquitous slogan: “Together We Prevail.”

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