diff --git a/gcc/cp/constraint.cc b/gcc/cp/constraint.cc
index 8cf0f2d0974..4c27f2a3a62 100644
--- a/gcc/cp/constraint.cc
+++ b/gcc/cp/constraint.cc
@@ -3751,6 +3751,9 @@ diagnose_trait_expr (tree expr, tree args)
     case CPTK_IS_UNION:
       inform (loc, "  %qT is not a union", t1);
       break;
+    case CPTK_IS_SCALAR:
+      inform (loc, "  %qT is not a scalar type", t1);
+      break;
     case CPTK_IS_AGGREGATE:
       inform (loc, "  %qT is not an aggregate", t1);
       break;
diff --git a/gcc/cp/cp-trait.def b/gcc/cp/cp-trait.def
index 8b7fece0cc8..59ae087c457 100644
--- a/gcc/cp/cp-trait.def
+++ b/gcc/cp/cp-trait.def
@@ -82,6 +82,7 @@ DEFTRAIT_EXPR (IS_TRIVIALLY_ASSIGNABLE, "__is_trivially_assignable", 2)
 DEFTRAIT_EXPR (IS_TRIVIALLY_CONSTRUCTIBLE, "__is_trivially_constructible", -1)
 DEFTRAIT_EXPR (IS_TRIVIALLY_COPYABLE, "__is_trivially_copyable", 1)
 DEFTRAIT_EXPR (IS_UNION, "__is_union", 1)
+DEFTRAIT_EXPR (IS_SCALAR, "__is_scalar", 1)
 DEFTRAIT_EXPR (REF_CONSTRUCTS_FROM_TEMPORARY, "__reference_constructs_from_temporary", 2)
 DEFTRAIT_EXPR (REF_CONVERTS_FROM_TEMPORARY, "__reference_converts_from_temporary", 2)
 /* FIXME Added space to avoid direct usage in GCC 13.  */
diff --git a/gcc/cp/semantics.cc b/gcc/cp/semantics.cc
index 8fb47fd179e..3edc7f23212 100644
--- a/gcc/cp/semantics.cc
+++ b/gcc/cp/semantics.cc
@@ -12118,6 +12118,9 @@ trait_expr_value (cp_trait_kind kind, tree type1, tree type2)
     case CPTK_IS_UNION:
       return type_code1 == UNION_TYPE;
 
+    case CPTK_IS_SCALAR:
+      return SCALAR_TYPE_P (type1);
+
     case CPTK_IS_ASSIGNABLE:
       return is_xible (MODIFY_EXPR, type1, type2);
 
@@ -12296,6 +12299,7 @@ finish_trait_expr (location_t loc, cp_trait_kind kind, tree type1, tree type2)
     case CPTK_IS_ENUM:
     case CPTK_IS_UNION:
     case CPTK_IS_SAME:
+    case CPTK_IS_SCALAR:
       break;
 
     case CPTK_IS_LAYOUT_COMPATIBLE:
diff --git a/gcc/testsuite/g++.dg/ext/has-builtin-1.C b/gcc/testsuite/g++.dg/ext/has-builtin-1.C
index f343e153e56..75acbdfb9fc 100644
--- a/gcc/testsuite/g++.dg/ext/has-builtin-1.C
+++ b/gcc/testsuite/g++.dg/ext/has-builtin-1.C
@@ -146,3 +146,6 @@
 #if !__has_builtin (__remove_cvref)
 # error "__has_builtin (__remove_cvref) failed"
 #endif
+#if !__has_builtin (__is_scalar)
+# error "__has_builtin (__is_scalar) failed"
+#endif
diff --git a/gcc/testsuite/g++.dg/ext/is_scalar.C b/gcc/testsuite/g++.dg/ext/is_scalar.C
new file mode 100644
index 00000000000..457fddc52fc
--- /dev/null
+++ b/gcc/testsuite/g++.dg/ext/is_scalar.C
@@ -0,0 +1,31 @@
+// { dg-do compile { target c++11 } }
+
+#include <cstddef>  // std::nullptr_t
+#include <testsuite_tr1.h>
+
+using namespace __gnu_test;
+
+#define SA(X) static_assert((X),#X)
+
+#define SA_TEST_CATEGORY(TRAIT, TYPE, EXPECT)	\
+  SA(TRAIT(TYPE) == EXPECT);					\
+  SA(TRAIT(const TYPE) == EXPECT);				\
+  SA(TRAIT(volatile TYPE) == EXPECT);			\
+  SA(TRAIT(const volatile TYPE) == EXPECT)
+
+// volatile return type would cause a warning.
+#define SA_FN_TEST_CATEGORY(TRAIT, TYPE, EXPECT)	\
+  SA(TRAIT(TYPE) == EXPECT);						\
+  SA(TRAIT(const TYPE) == EXPECT)
+
+SA_TEST_CATEGORY(__is_scalar, int, true);
+SA_TEST_CATEGORY(__is_scalar, float, true);
+SA_TEST_CATEGORY(__is_scalar, EnumType, true);
+SA_TEST_CATEGORY(__is_scalar, int*, true);
+SA_FN_TEST_CATEGORY(__is_scalar, int(*)(int), true);
+SA_TEST_CATEGORY(__is_scalar, int (ClassType::*), true);
+SA_FN_TEST_CATEGORY(__is_scalar, int (ClassType::*) (int), true);
+SA_TEST_CATEGORY(__is_scalar, std::nullptr_t, true);
+
+// Sanity check.
+SA_TEST_CATEGORY(__is_scalar, ClassType, false);
diff --git a/gcc/testsuite/g++.dg/tm/pr46567.C b/gcc/testsuite/g++.dg/tm/pr46567.C
index 6d791484448..d79e0afb462 100644
--- a/gcc/testsuite/g++.dg/tm/pr46567.C
+++ b/gcc/testsuite/g++.dg/tm/pr46567.C
@@ -225,7 +225,7 @@ namespace std __attribute__ ((__visibility__ ("default"))) {
     : public __traitor<__is_void<_Tp>, __is_arithmetic<_Tp> >
     { };
   template<typename _Tp>
-    struct __is_scalar
+    struct ____is_scalar
     : public __traitor<__is_arithmetic<_Tp>, __is_pointer<_Tp> >
     { };
   template<typename _Tp>
@@ -1325,7 +1325,7 @@ namespace std __attribute__ ((__visibility__ ("default"))) {
     }
   template<typename _ForwardIterator, typename _Tp>
     inline typename
-    __gnu_cxx::__enable_if<!__is_scalar<_Tp>::__value, void>::__type
+    __gnu_cxx::__enable_if<!____is_scalar<_Tp>::__value, void>::__type
     __fill_a(_ForwardIterator __first, _ForwardIterator __last,
        const _Tp& __value)
     {
@@ -1334,7 +1334,7 @@ namespace std __attribute__ ((__visibility__ ("default"))) {
     }
   template<typename _ForwardIterator, typename _Tp>
     inline typename
-    __gnu_cxx::__enable_if<__is_scalar<_Tp>::__value, void>::__type
+    __gnu_cxx::__enable_if<____is_scalar<_Tp>::__value, void>::__type
     __fill_a(_ForwardIterator __first, _ForwardIterator __last,
       const _Tp& __value)
     {
@@ -1362,7 +1362,7 @@ namespace std __attribute__ ((__visibility__ ("default"))) {
     }
   template<typename _OutputIterator, typename _Size, typename _Tp>
     inline typename
-    __gnu_cxx::__enable_if<!__is_scalar<_Tp>::__value, _OutputIterator>::__type
+    __gnu_cxx::__enable_if<!____is_scalar<_Tp>::__value, _OutputIterator>::__type
     __fill_n_a(_OutputIterator __first, _Size __n, const _Tp& __value)
     {
       for (; __n > 0; --__n, ++__first)
@@ -1371,7 +1371,7 @@ namespace std __attribute__ ((__visibility__ ("default"))) {
     }
   template<typename _OutputIterator, typename _Size, typename _Tp>
     inline typename
-    __gnu_cxx::__enable_if<__is_scalar<_Tp>::__value, _OutputIterator>::__type
+    __gnu_cxx::__enable_if<____is_scalar<_Tp>::__value, _OutputIterator>::__type
     __fill_n_a(_OutputIterator __first, _Size __n, const _Tp& __value)
     {
       const _Tp __tmp = __value;
diff --git a/gcc/testsuite/g++.dg/torture/pr57107.C b/gcc/testsuite/g++.dg/torture/pr57107.C
index 4dbd32bd298..65fd74ded9a 100644
--- a/gcc/testsuite/g++.dg/torture/pr57107.C
+++ b/gcc/testsuite/g++.dg/torture/pr57107.C
@@ -27,7 +27,7 @@ namespace std __attribute__ ((__visibility__ ("default"))) {
     };
     template<typename _Tp>     struct __is_arithmetic     : public __traitor<__is_integer<_Tp>, __is_floating<_Tp> >     {
     };
-    template<typename _Tp>     struct __is_scalar     : public __traitor<__is_arithmetic<_Tp>, __is_pointer<_Tp> >     {
+    template<typename _Tp>     struct ____is_scalar     : public __traitor<__is_arithmetic<_Tp>, __is_pointer<_Tp> >     {
     };
 }
 namespace __gnu_cxx __attribute__ ((__visibility__ ("default"))) {
@@ -54,7 +54,7 @@ namespace std __attribute__ ((__visibility__ ("default"))) {
     };
     template<typename _Iterator>     inline typename _Niter_base<_Iterator>::iterator_type     __niter_base(_Iterator __it)     {
     }
-    template<typename _OutputIterator, typename _Size, typename _Tp>     inline typename     __gnu_cxx::__enable_if<!__is_scalar<_Tp>::__value, _OutputIterator>::__type     __fill_n_a(_OutputIterator __first, _Size __n, const _Tp& __value)     {
+    template<typename _OutputIterator, typename _Size, typename _Tp>     inline typename     __gnu_cxx::__enable_if<!____is_scalar<_Tp>::__value, _OutputIterator>::__type     __fill_n_a(_OutputIterator __first, _Size __n, const _Tp& __value)     {
 	for (__decltype(__n + 0) __niter = __n;
 	     __niter > 0;
 	     --__niter, ++__first)  *__first = __value;
diff --git a/libstdc++-v3/include/bits/cpp_type_traits.h b/libstdc++-v3/include/bits/cpp_type_traits.h
index 4312f32a4e0..f7f0d558421 100644
--- a/libstdc++-v3/include/bits/cpp_type_traits.h
+++ b/libstdc++-v3/include/bits/cpp_type_traits.h
@@ -389,7 +389,7 @@ __INT_N(__GLIBCXX_TYPE_INT_N_3)
   // A scalar type is an arithmetic type or a pointer type
   // 
   template<typename _Tp>
-    struct __is_scalar
+    struct ____is_scalar
     : public __traitor<__is_arithmetic<_Tp>, __is_pointer<_Tp> >
     { };
 
diff --git a/libstdc++-v3/include/bits/stl_algobase.h b/libstdc++-v3/include/bits/stl_algobase.h
index dd95e94f7e9..f292d26fbf0 100644
--- a/libstdc++-v3/include/bits/stl_algobase.h
+++ b/libstdc++-v3/include/bits/stl_algobase.h
@@ -911,7 +911,7 @@ _GLIBCXX_END_NAMESPACE_CONTAINER
   template<typename _ForwardIterator, typename _Tp>
     _GLIBCXX20_CONSTEXPR
     inline typename
-    __gnu_cxx::__enable_if<!__is_scalar<_Tp>::__value, void>::__type
+    __gnu_cxx::__enable_if<!____is_scalar<_Tp>::__value, void>::__type
     __fill_a1(_ForwardIterator __first, _ForwardIterator __last,
 	      const _Tp& __value)
     {
@@ -922,7 +922,7 @@ _GLIBCXX_END_NAMESPACE_CONTAINER
   template<typename _ForwardIterator, typename _Tp>
     _GLIBCXX20_CONSTEXPR
     inline typename
-    __gnu_cxx::__enable_if<__is_scalar<_Tp>::__value, void>::__type
+    __gnu_cxx::__enable_if<____is_scalar<_Tp>::__value, void>::__type
     __fill_a1(_ForwardIterator __first, _ForwardIterator __last,
 	      const _Tp& __value)
     {
@@ -1060,7 +1060,7 @@ _GLIBCXX_END_NAMESPACE_CONTAINER
   template<typename _OutputIterator, typename _Size, typename _Tp>
     _GLIBCXX20_CONSTEXPR
     inline typename
-    __gnu_cxx::__enable_if<!__is_scalar<_Tp>::__value, _OutputIterator>::__type
+    __gnu_cxx::__enable_if<!____is_scalar<_Tp>::__value, _OutputIterator>::__type
     __fill_n_a1(_OutputIterator __first, _Size __n, const _Tp& __value)
     {
       for (; __n > 0; --__n, (void) ++__first)
@@ -1071,7 +1071,7 @@ _GLIBCXX_END_NAMESPACE_CONTAINER
   template<typename _OutputIterator, typename _Size, typename _Tp>
     _GLIBCXX20_CONSTEXPR
     inline typename
-    __gnu_cxx::__enable_if<__is_scalar<_Tp>::__value, _OutputIterator>::__type
+    __gnu_cxx::__enable_if<____is_scalar<_Tp>::__value, _OutputIterator>::__type
     __fill_n_a1(_OutputIterator __first, _Size __n, const _Tp& __value)
     {
       const _Tp __tmp = __value;
diff --git a/libstdc++-v3/include/bits/valarray_array.h b/libstdc++-v3/include/bits/valarray_array.h
index 222fd5fd900..682770ad7db 100644
--- a/libstdc++-v3/include/bits/valarray_array.h
+++ b/libstdc++-v3/include/bits/valarray_array.h
@@ -90,7 +90,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     inline void
     __valarray_default_construct(_Tp* __b, _Tp* __e)
     {
-      _Array_default_ctor<_Tp, __is_scalar<_Tp>::__value>::_S_do_it(__b, __e);
+      _Array_default_ctor<_Tp, ____is_scalar<_Tp>::__value>::_S_do_it(__b, __e);
     }
 
   // Turn a raw-memory into an array of _Tp filled with __t
