Index: clang/lib/Format/TokenAnnotator.cpp
===================================================================
--- clang/lib/Format/TokenAnnotator.cpp
+++ clang/lib/Format/TokenAnnotator.cpp
@@ -2940,6 +2940,10 @@
       return true;
   }
 
+  // auto{x}
+  if (Left.is(tok::kw_auto) && Right.isOneOf(tok::l_paren, tok::l_brace))
+    return false;
+
   // requires clause Concept1<T> && Concept2<T>
   if (Left.is(TT_ConstraintJunctions) && Right.is(tok::identifier))
     return true;
Index: clang/unittests/Format/FormatTest.cpp
===================================================================
--- clang/unittests/Format/FormatTest.cpp
+++ clang/unittests/Format/FormatTest.cpp
@@ -22566,6 +22566,22 @@
   EXPECT_EQ(Code, format(Code, Style));
 }
 
+TEST_F(FormatTest, FormatDecayCopy) {
+  verifyFormat("foo(auto())");
+  verifyFormat("foo(auto{})");
+  verifyFormat("foo(auto({}))");
+  verifyFormat("foo(auto{{}})");
+  verifyFormat("foo(auto(1))");
+  verifyFormat("foo(auto{1})");
+  verifyFormat("foo(new auto(1))");
+  verifyFormat("foo(new auto{1})");
+  verifyFormat("decltype(auto(1)) x;");
+  verifyFormat("decltype(auto{1}) x;");
+  verifyFormat("auto(x);");
+  verifyFormat("auto{x};");
+  verifyFormat("auto{x} = y;");
+}
+
 } // namespace
 } // namespace format
 } // namespace clang