diff --git a/libcxx/include/__cxx03/__algorithm/count.h b/libcxx/include/__cxx03/__algorithm/count.h
index 5440fd031a1d3..5b05b4b71f519 100644
--- a/libcxx/include/__cxx03/__algorithm/count.h
+++ b/libcxx/include/__cxx03/__algorithm/count.h
@@ -54,18 +54,18 @@ __count_bool(__bit_iterator<_Cp, _IsConst> __first, typename _Cp::size_type __n)
   if (__first.__ctz_ != 0) {
     __storage_type __clz_f = static_cast<__storage_type>(__bits_per_word - __first.__ctz_);
     __storage_type __dn    = std::min(__clz_f, __n);
-    __storage_type __m     = (~__storage_type(0) << __first.__ctz_) & (~__storage_type(0) >> (__clz_f - __dn));
-    __r                    = std::__libcpp_popcount(std::__invert_if<!_ToCount>(*__first.__seg_) & __m);
+    __storage_type __m     = (__storage_type(~0) << __first.__ctz_) & (__storage_type(~0) >> (__clz_f - __dn));
+    __r                    = std::__libcpp_popcount<__storage_type>(std::__invert_if<!_ToCount>(*__first.__seg_) & __m);
     __n -= __dn;
     ++__first.__seg_;
   }
   // do middle whole words
   for (; __n >= __bits_per_word; ++__first.__seg_, __n -= __bits_per_word)
-    __r += std::__libcpp_popcount(std::__invert_if<!_ToCount>(*__first.__seg_));
+    __r += std::__libcpp_popcount<__storage_type>(std::__invert_if<!_ToCount>(*__first.__seg_));
   // do last partial word
   if (__n > 0) {
-    __storage_type __m = ~__storage_type(0) >> (__bits_per_word - __n);
-    __r += std::__libcpp_popcount(std::__invert_if<!_ToCount>(*__first.__seg_) & __m);
+    __storage_type __m = __storage_type(~0) >> (__bits_per_word - __n);
+    __r += std::__libcpp_popcount<__storage_type>(std::__invert_if<!_ToCount>(*__first.__seg_) & __m);
   }
   return __r;
 }
diff --git a/libcxx/include/__cxx03/__bit/popcount.h b/libcxx/include/__cxx03/__bit/popcount.h
index 64404d2cf4948..a61a92177c5b7 100644
--- a/libcxx/include/__cxx03/__bit/popcount.h
+++ b/libcxx/include/__cxx03/__bit/popcount.h
@@ -6,9 +6,6 @@
 //
 //===----------------------------------------------------------------------===//
 
-// TODO: __builtin_popcountg is available since Clang 19 and GCC 14. When support for older versions is dropped, we can
-//  refactor this code to exclusively use __builtin_popcountg.
-
 #ifndef _LIBCPP___CXX03___BIT_POPCOUNT_H
 #define _LIBCPP___CXX03___BIT_POPCOUNT_H
 
@@ -25,12 +22,9 @@ _LIBCPP_PUSH_MACROS
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
-inline _LIBCPP_HIDE_FROM_ABI int __libcpp_popcount(unsigned __x) _NOEXCEPT { return __builtin_popcount(__x); }
-
-inline _LIBCPP_HIDE_FROM_ABI int __libcpp_popcount(unsigned long __x) _NOEXCEPT { return __builtin_popcountl(__x); }
-
-inline _LIBCPP_HIDE_FROM_ABI int __libcpp_popcount(unsigned long long __x) _NOEXCEPT {
-  return __builtin_popcountll(__x);
+template <class _Tp>
+_LIBCPP_HIDE_FROM_ABI int __libcpp_popcount(_Tp __v) {
+  return __builtin_popcountg(__v);
 }
 
 _LIBCPP_END_NAMESPACE_STD
diff --git a/libcxx/test/std/algorithms/alg.nonmodifying/alg.count/count.pass.cpp b/libcxx/test/std/algorithms/alg.nonmodifying/alg.count/count.pass.cpp
index e696dcdb34351..ffe3e0ef746c1 100644
--- a/libcxx/test/std/algorithms/alg.nonmodifying/alg.count/count.pass.cpp
+++ b/libcxx/test/std/algorithms/alg.nonmodifying/alg.count/count.pass.cpp
@@ -15,7 +15,6 @@
 
 // ADDITIONAL_COMPILE_FLAGS(has-fconstexpr-steps): -fconstexpr-steps=20000000
 // ADDITIONAL_COMPILE_FLAGS(has-fconstexpr-ops-limit): -fconstexpr-ops-limit=80000000
-// XFAIL: FROZEN-CXX03-HEADERS-FIXME
 
 #include <algorithm>
 #include <cassert>