diff --git a/Eigen/src/Core/NumTraits.h b/Eigen/src/Core/NumTraits.h
index 5e4e5c2ff..b93faae26 100644
--- a/Eigen/src/Core/NumTraits.h
+++ b/Eigen/src/Core/NumTraits.h
@@ -95,9 +95,19 @@ struct default_max_digits10_impl<T, false, true>  // Integer
 }  // end namespace internal
 
 namespace numext {
-/** \internal bit-wise cast without changing the underlying bit representation. */
 
-// TODO: Replace by std::bit_cast (available in C++20)
+/** \internal bit-wise cast without changing the underlying bit representation. */
+#if defined(__cpp_lib_bit_cast) && __cpp_lib_bit_cast >= 201806L
+EIGEN_STRONG_INLINE EIGEN_DEVICE_FUNC constexpr Tgt bit_cast(const Src& src) { return std::bit_cast<Tgt>(src); }
+#elif EIGEN_HAS_BUILTIN(__builtin_bit_cast)
+template <typename Tgt, typename Src>
+EIGEN_STRONG_INLINE EIGEN_DEVICE_FUNC constexpr Tgt bit_cast(const Src& src) {
+  EIGEN_STATIC_ASSERT(std::is_trivially_copyable<Src>::value, THIS_TYPE_IS_NOT_SUPPORTED)
+  EIGEN_STATIC_ASSERT(std::is_trivially_copyable<Tgt>::value, THIS_TYPE_IS_NOT_SUPPORTED)
+  EIGEN_STATIC_ASSERT(sizeof(Src) == sizeof(Tgt), THIS_TYPE_IS_NOT_SUPPORTED)
+  return __builtin_bit_cast(Tgt, src);
+}
+#else
 template <typename Tgt, typename Src>
 EIGEN_STRONG_INLINE EIGEN_DEVICE_FUNC Tgt bit_cast(const Src& src) {
   // The behaviour of memcpy is not specified for non-trivially copyable types
@@ -113,6 +123,7 @@ EIGEN_STRONG_INLINE EIGEN_DEVICE_FUNC Tgt bit_cast(const Src& src) {
   memcpy(static_cast<void*>(&tgt), static_cast<const void*>(&staged), sizeof(Tgt));
   return tgt;
 }
+#endif
 }  // namespace numext
 
 // clang-format off