diff --git a/clang/lib/CodeGen/CGBuiltin.cpp b/clang/lib/CodeGen/CGBuiltin.cpp
--- a/clang/lib/CodeGen/CGBuiltin.cpp
+++ b/clang/lib/CodeGen/CGBuiltin.cpp
@@ -14295,7 +14295,7 @@
     Value *Y = EmitScalarExpr(E->getArg(1));
     ID = Intrinsic::copysign;
     llvm::Function *F = CGM.getIntrinsic(ID, ResultType);
-    return Builder.CreateCall(F, {X, Y});
+    return Builder.CreateCall(F, {Y, X});
   }
   // Rounding/truncation
   case PPC::BI__builtin_vsx_xvrspip: