diff --git a/compiler/src/dmd/cparse.d b/compiler/src/dmd/cparse.d
index 3ad7ed093c..f3b863c324 100644
--- a/compiler/src/dmd/cparse.d
+++ b/compiler/src/dmd/cparse.d
@@ -982,6 +982,7 @@ final class CParser(AST) : Parser!AST
      *    sizeof unary-expression
      *    sizeof ( type-name )
      *    _Alignof ( type-name )
+     *    _Alignof unary-expression // gcc extension
      *
      * unary-operator:
      *    & * + - ~ !
@@ -1044,8 +1045,10 @@ final class CParser(AST) : Parser!AST
             e = new AST.ComExp(loc, e);
             break;
 
+        case TOK._Alignof:
         case TOK.sizeof_:
         {
+            Identifier id = token.value == TOK.sizeof_? Id.__sizeof : Id.__xalignof;
             nextToken();
             if (token.value == TOK.leftParenthesis)
             {
@@ -1084,7 +1087,7 @@ final class CParser(AST) : Parser!AST
                 e = cparseUnaryExp();
             }
 
-            e = new AST.DotIdExp(loc, e, Id.__sizeof);
+            e = new AST.DotIdExp(loc, e, id);
             break;
         }
 
@@ -1096,17 +1099,6 @@ final class CParser(AST) : Parser!AST
             e = cparseCastExp();
             break;
 
-        case TOK._Alignof:
-        {
-            nextToken();
-            check(TOK.leftParenthesis);
-            auto t = cparseTypeName();
-            check(TOK.rightParenthesis);
-            e = new AST.TypeExp(loc, t);
-            e = new AST.DotIdExp(loc, e, Id.__xalignof);
-            break;
-        }
-
         default:
             e = cparsePostfixExp(e);
             break;
@@ -5025,6 +5017,7 @@ final class CParser(AST) : Parser!AST
                     return false;
                 break;
 
+            case TOK._Alignof:
             case TOK.sizeof_:
                 t = peek(t);
                 if (t.value == TOK.leftParenthesis)
@@ -5042,15 +5035,6 @@ final class CParser(AST) : Parser!AST
                     return false;
                 break;
 
-            case TOK._Alignof:
-                t = peek(t);
-                if (t.value != TOK.leftParenthesis)
-                    return false;
-                t = peek(t);
-                if (!isTypeName(t) || t.value != TOK.rightParenthesis)
-                    return false;
-                break;
-
             default:
                 // Compound literals are handled by cast and sizeof expressions,
                 // so be content with just seeing a primary expression.
diff --git a/compiler/src/dmd/expressionsem.d b/compiler/src/dmd/expressionsem.d
index 61ef350bde..e5f9e301a2 100644
--- a/compiler/src/dmd/expressionsem.d
+++ b/compiler/src/dmd/expressionsem.d
@@ -8191,37 +8191,7 @@ private extern (C++) final class ExpressionSemanticVisitor : Visitor
             if (exp.arrow) // ImportC only
                 exp.e1 = exp.e1.expressionSemantic(sc).arrayFuncConv(sc);
 
-            if (exp.ident == Id.__xalignof && exp.e1.isTypeExp())
-            {
-                // C11 6.5.3 says _Alignof only applies to types
-                Expression e;
-                Type t;
-                Dsymbol s;
-                dmd.typesem.resolve(exp.e1.type, exp.e1.loc, sc, e, t, s, true);
-                if (e)
-                {
-                    error(exp.e1.loc, "argument to `_Alignof` must be a type");
-                    return setError();
-                }
-                else if (t)
-                {
-                    // Note similarity to getProperty() implementation of __xalignof
-                    const explicitAlignment = t.alignment();
-                    const naturalAlignment = t.alignsize();
-                    const actualAlignment = (explicitAlignment.isDefault() ? naturalAlignment : explicitAlignment.get());
-                    result = new IntegerExp(exp.loc, actualAlignment, Type.tsize_t);
-                }
-                else if (s)
-                {
-                    error(exp.e1.loc, "argument to `_Alignof` must be a type");
-                    return setError();
-                }
-                else
-                    assert(0);
-                return;
-            }
-
-            if (exp.ident != Id.__sizeof)
+            if (exp.ident != Id.__sizeof && exp.ident != Id.__xalignof)
             {
                 result = fieldLookup(exp.e1, sc, exp.ident, exp.arrow);
                 return;
diff --git a/compiler/test/compilable/alignas.c b/compiler/test/compilable/alignas.c
index 1631ab61e2..623a2f8394 100644
--- a/compiler/test/compilable/alignas.c
+++ b/compiler/test/compilable/alignas.c
@@ -3,10 +3,10 @@
 int printf(const char *, ...);
 
 _Alignas(4) _Alignas(8) _Alignas(0) int x = 5;
-//_Static_assert(_Alignof(x) == 8, "in");
+_Static_assert(_Alignof(x) == 8, "in");
 
 _Alignas(int) short y = 6;
-//_Static_assert(_Alignof(y) == 4, "in");
+_Static_assert(_Alignof(y) == 4, "in");
 
 struct S
 {
diff --git a/compiler/test/compilable/testcstuff1.c b/compiler/test/compilable/testcstuff1.c
index db0f59058f..5b92f507fd 100644
--- a/compiler/test/compilable/testcstuff1.c
+++ b/compiler/test/compilable/testcstuff1.c
@@ -329,6 +329,7 @@ void test4(int i)
     _Static_assert(sizeof 3 == 4, "ok");
     _Static_assert(sizeof(3) == 4, "ok");
     _Static_assert(_Alignof(int) == 4, "ok");
+    _Static_assert(_Alignof 3  == 4, "ok");
     _Static_assert((int)3 == 3, "ok");
     _Static_assert(sizeof p[0] == 4, "ok");
     _Static_assert(1 && 2, "ok");
diff --git a/compiler/test/fail_compilation/test22246.c b/compiler/test/fail_compilation/test22246.c
deleted file mode 100644
index ff71913396..0000000000
--- a/compiler/test/fail_compilation/test22246.c
+++ /dev/null
@@ -1,17 +0,0 @@
-/* TEST_OUTPUT:
----
-fail_compilation/test22246.c(106): Error: argument to `_Alignof` must be a type
----
-*/
-
-// https://issues.dlang.org/show_bug.cgi?id=22246
-
-#line 100
-
-struct S { int m; };
-
-int test()
-{
-    struct S s;
-    return _Alignof(s);
-}