diff --git a/libcxx/CMakeLists.txt b/libcxx/CMakeLists.txt
index a119850cd808e..d7f4ca1bfb40c 100644
--- a/libcxx/CMakeLists.txt
+++ b/libcxx/CMakeLists.txt
@@ -668,6 +668,10 @@ function(cxx_link_system_libraries target)
     target_link_libraries(${target} PRIVATE atomic)
   endif()
 
+  if (LIBCXX_HAS_MATH_LIB)
+    target_link_libraries(${target} PRIVATE m)
+  endif()
+
   if (MINGW)
     target_link_libraries(${target} PRIVATE "${MINGW_LIBRARIES}")
   endif()
diff --git a/libcxx/cmake/config-ix.cmake b/libcxx/cmake/config-ix.cmake
index 270d80575adcf..80eeda05b302a 100644
--- a/libcxx/cmake/config-ix.cmake
+++ b/libcxx/cmake/config-ix.cmake
@@ -110,24 +110,30 @@ if(WIN32 AND NOT MINGW)
   set(LIBCXX_HAS_PTHREAD_LIB NO)
   set(LIBCXX_HAS_RT_LIB NO)
   set(LIBCXX_HAS_ATOMIC_LIB NO)
+  set(LIBCXX_HAS_MATH_LIB NO)
 elseif(APPLE)
   set(LIBCXX_HAS_PTHREAD_LIB NO)
   set(LIBCXX_HAS_RT_LIB NO)
   set(LIBCXX_HAS_ATOMIC_LIB NO)
+  set(LIBCXX_HAS_MATH_LIB NO)
 elseif(FUCHSIA)
   set(LIBCXX_HAS_PTHREAD_LIB NO)
   set(LIBCXX_HAS_RT_LIB NO)
   check_library_exists(atomic __atomic_fetch_add_8 "" LIBCXX_HAS_ATOMIC_LIB)
+  set(LIBCXX_HAS_MATH_LIB NO)
 elseif(ANDROID)
   set(LIBCXX_HAS_PTHREAD_LIB NO)
   set(LIBCXX_HAS_RT_LIB NO)
   set(LIBCXX_HAS_ATOMIC_LIB NO)
+  set(LIBCXX_HAS_MATH_LIB NO)
 elseif(PICOLIBC)
   set(LIBCXX_HAS_PTHREAD_LIB NO)
   set(LIBCXX_HAS_RT_LIB NO)
   set(LIBCXX_HAS_ATOMIC_LIB NO)
+  set(LIBCXX_HAS_MATH_LIB NO)
 else()
   check_library_exists(pthread pthread_create "" LIBCXX_HAS_PTHREAD_LIB)
   check_library_exists(rt clock_gettime "" LIBCXX_HAS_RT_LIB)
   check_library_exists(atomic __atomic_fetch_add_8 "" LIBCXX_HAS_ATOMIC_LIB)
+  check_library_exists(m lgamma_r "" LIBCXX_HAS_MATH_LIB)
 endif()
diff --git a/libcxx/include/__configuration/availability.h b/libcxx/include/__configuration/availability.h
index 2fbc34a3cf8a2..615213821e503 100644
--- a/libcxx/include/__configuration/availability.h
+++ b/libcxx/include/__configuration/availability.h
@@ -84,6 +84,9 @@
 // in all versions of the library are available.
 #if !_LIBCPP_HAS_VENDOR_AVAILABILITY_ANNOTATIONS
 
+#  define _LIBCPP_INTRODUCED_IN_LLVM_22 1
+#  define _LIBCPP_INTRODUCED_IN_LLVM_22_ATTRIBUTE /* nothing */
+
 #  define _LIBCPP_INTRODUCED_IN_LLVM_21 1
 #  define _LIBCPP_INTRODUCED_IN_LLVM_21_ATTRIBUTE /* nothing */
 
@@ -120,6 +123,11 @@
 
 // clang-format off
 
+// LLVM 22
+// TODO: Fill this in
+#  define _LIBCPP_INTRODUCED_IN_LLVM_22 0
+#  define _LIBCPP_INTRODUCED_IN_LLVM_22_ATTRIBUTE __attribute__((unavailable))
+
 // LLVM 21
 // TODO: Fill this in
 #  define _LIBCPP_INTRODUCED_IN_LLVM_21 0
@@ -355,6 +363,11 @@
 #define _LIBCPP_AVAILABILITY_HAS_BAD_FUNCTION_CALL_GOOD_WHAT_MESSAGE _LIBCPP_INTRODUCED_IN_LLVM_21
 // No attribute, since we've had bad_function_call::what() in the headers before
 
+// This controls whether we provide an implementation of a thread safe variant of the `std::lgamma`
+// function in the dylib.
+#define _LIBCPP_AVAILABILITY_HAS_THREAD_SAFE_LGAMMA _LIBCPP_INTRODUCED_IN_LLVM_22
+// No attribute, since we call ::lgamma_r instead
+
 // Define availability attributes that depend on both
 // _LIBCPP_HAS_EXCEPTIONS and _LIBCPP_HAS_RTTI.
 #if !_LIBCPP_HAS_EXCEPTIONS || !_LIBCPP_HAS_RTTI
diff --git a/libcxx/include/__math/gamma.h b/libcxx/include/__math/gamma.h
index 693e111a84e99..66fce3b5646de 100644
--- a/libcxx/include/__math/gamma.h
+++ b/libcxx/include/__math/gamma.h
@@ -55,6 +55,31 @@ inline _LIBCPP_HIDE_FROM_ABI double tgamma(_A1 __x) _NOEXCEPT {
   return __builtin_tgamma((double)__x);
 }
 
+// __lgamma_r
+
+struct __lgamma_result {
+  double __result;
+  int __sign;
+};
+
+#if _LIBCPP_AVAILABILITY_HAS_THREAD_SAFE_LGAMMA
+_LIBCPP_EXPORTED_FROM_ABI __lgamma_result __lgamma_thread_safe_impl(double) _NOEXCEPT;
+
+inline _LIBCPP_HIDE_FROM_ABI __lgamma_result __lgamma_thread_safe(double __d) _NOEXCEPT {
+  return __math::__lgamma_thread_safe_impl(__d);
+}
+#else
+// When deploying to older targets, call `lgamma_r` directly but avoid declaring the actual
+// function since different platforms declare the function slightly differently.
+double __lgamma_r_shim(double, int*) _NOEXCEPT __asm__("lgamma_r");
+
+inline _LIBCPP_HIDE_FROM_ABI __lgamma_result __lgamma_thread_safe(double __d) _NOEXCEPT {
+  int __sign;
+  double __res = __math::__lgamma_r_shim(__d, &__sign);
+  return __lgamma_result{__res, __sign};
+}
+#endif
+
 } // namespace __math
 
 _LIBCPP_END_NAMESPACE_STD
diff --git a/libcxx/include/__random/binomial_distribution.h b/libcxx/include/__random/binomial_distribution.h
index bada8cfdd74a3..2b74c592306b9 100644
--- a/libcxx/include/__random/binomial_distribution.h
+++ b/libcxx/include/__random/binomial_distribution.h
@@ -10,6 +10,7 @@
 #define _LIBCPP___RANDOM_BINOMIAL_DISTRIBUTION_H
 
 #include <__config>
+#include <__math/gamma.h>
 #include <__random/is_valid.h>
 #include <__random/uniform_real_distribution.h>
 #include <cmath>
@@ -97,39 +98,14 @@ class binomial_distribution {
   }
 };
 
-// Some libc declares the math functions to be `noexcept`.
-#if defined(_LIBCPP_GLIBC_PREREQ)
-#  if _LIBCPP_GLIBC_PREREQ(2, 8)
-#    define _LIBCPP_LGAMMA_R_NOEXCEPT _NOEXCEPT
-#  else
-#    define _LIBCPP_LGAMMA_R_NOEXCEPT
-#  endif
-#elif defined(__LLVM_LIBC__)
-#  define _LIBCPP_LGAMMA_R_NOEXCEPT _NOEXCEPT
-#else
-#  define _LIBCPP_LGAMMA_R_NOEXCEPT
-#endif
-
-#if !defined(_LIBCPP_MSVCRT_LIKE)
-extern "C" double lgamma_r(double, int*) _LIBCPP_LGAMMA_R_NOEXCEPT;
-#endif
-
-inline _LIBCPP_HIDE_FROM_ABI double __libcpp_lgamma(double __d) {
-#if defined(_LIBCPP_MSVCRT_LIKE)
-  return lgamma(__d);
-#else
-  int __sign;
-  return lgamma_r(__d, &__sign);
-#endif
-}
-
 template <class _IntType>
 binomial_distribution<_IntType>::param_type::param_type(result_type __t, double __p) : __t_(__t), __p_(__p) {
   if (0 < __p_ && __p_ < 1) {
     __r0_ = static_cast<result_type>((__t_ + 1) * __p_);
-    __pr_ = std::exp(
-        std::__libcpp_lgamma(__t_ + 1.) - std::__libcpp_lgamma(__r0_ + 1.) - std::__libcpp_lgamma(__t_ - __r0_ + 1.) +
-        __r0_ * std::log(__p_) + (__t_ - __r0_) * std::log(1 - __p_));
+    __pr_ =
+        std::exp(__math::__lgamma_thread_safe(__t_ + 1.).__result - __math::__lgamma_thread_safe(__r0_ + 1.).__result -
+                 __math::__lgamma_thread_safe(__t_ - __r0_ + 1.).__result + __r0_ * std::log(__p_) +
+                 (__t_ - __r0_) * std::log(1 - __p_));
     __odds_ratio_ = __p_ / (1 - __p_);
   }
 }
diff --git a/libcxx/lib/abi/CHANGELOG.TXT b/libcxx/lib/abi/CHANGELOG.TXT
index 968dc7a22a8c7..f6064bf052687 100644
--- a/libcxx/lib/abi/CHANGELOG.TXT
+++ b/libcxx/lib/abi/CHANGELOG.TXT
@@ -16,6 +16,16 @@ New entries should be added directly below the "Version" header.
 Version 22.0
 ------------
 
+* [libc++] Add a thread-safe version of std::lgamma in the dylib
+
+  This patch adds a new function __lgamma_thread_safe in the dylib to avoid having to redeclare
+  ::lgamma_r within libc++'s own headers. This merely introduces a new symbol so it's not an ABI
+  break.
+
+  All platforms
+  -------------
+  Symbol added: _ZNSt3__16__math25__lgamma_thread_safe_implEd
+
 * [libc++] Remove __time_get_storage::{__analyze,init} from the ABI
 
   These functions have never been used outside the dylib, so there is no point in exporting them.
diff --git a/libcxx/lib/abi/arm64-apple-darwin.libcxxabi.v1.stable.exceptions.nonew.abilist b/libcxx/lib/abi/arm64-apple-darwin.libcxxabi.v1.stable.exceptions.nonew.abilist
index 3a1d8950c2db0..f5da8dabefe48 100644
--- a/libcxx/lib/abi/arm64-apple-darwin.libcxxabi.v1.stable.exceptions.nonew.abilist
+++ b/libcxx/lib/abi/arm64-apple-darwin.libcxxabi.v1.stable.exceptions.nonew.abilist
@@ -1692,6 +1692,7 @@
 {'is_defined': True, 'name': '__ZNSt3__15wcoutE', 'size': 0, 'type': 'OBJECT'}
 {'is_defined': True, 'name': '__ZNSt3__16__itoa8__u32toaEjPc', 'type': 'FUNC'}
 {'is_defined': True, 'name': '__ZNSt3__16__itoa8__u64toaEyPc', 'type': 'FUNC'}
+{'is_defined': True, 'name': '__ZNSt3__16__math25__lgamma_thread_safe_implEd', 'type': 'FUNC'}
 {'is_defined': True, 'name': '__ZNSt3__16__sortIRNS_6__lessIaaEEPaEEvT0_S5_T_', 'type': 'FUNC'}
 {'is_defined': True, 'name': '__ZNSt3__16__sortIRNS_6__lessIccEEPcEEvT0_S5_T_', 'type': 'FUNC'}
 {'is_defined': True, 'name': '__ZNSt3__16__sortIRNS_6__lessIddEEPdEEvT0_S5_T_', 'type': 'FUNC'}
diff --git a/libcxx/lib/abi/i686-linux-android21.libcxxabi.v1.stable.exceptions.nonew.abilist b/libcxx/lib/abi/i686-linux-android21.libcxxabi.v1.stable.exceptions.nonew.abilist
index 313de84df20e8..92dedea3e6a1b 100644
--- a/libcxx/lib/abi/i686-linux-android21.libcxxabi.v1.stable.exceptions.nonew.abilist
+++ b/libcxx/lib/abi/i686-linux-android21.libcxxabi.v1.stable.exceptions.nonew.abilist
@@ -1329,6 +1329,7 @@
 {'is_defined': True, 'name': '_ZNSt6__ndk16__clocEv', 'type': 'FUNC'}
 {'is_defined': True, 'name': '_ZNSt6__ndk16__itoa8__u32toaEjPc', 'type': 'FUNC'}
 {'is_defined': True, 'name': '_ZNSt6__ndk16__itoa8__u64toaEyPc', 'type': 'FUNC'}
+{'is_defined': True, 'name': '_ZNSt6__ndk16__math25__lgamma_thread_safe_implEd', 'type': 'FUNC'}
 {'is_defined': True, 'name': '_ZNSt6__ndk16__sortIRNS_6__lessIaaEEPaEEvT0_S5_T_', 'type': 'FUNC'}
 {'is_defined': True, 'name': '_ZNSt6__ndk16__sortIRNS_6__lessIccEEPcEEvT0_S5_T_', 'type': 'FUNC'}
 {'is_defined': True, 'name': '_ZNSt6__ndk16__sortIRNS_6__lessIddEEPdEEvT0_S5_T_', 'type': 'FUNC'}
diff --git a/libcxx/lib/abi/powerpc-ibm-aix.libcxxabi.v1.stable.exceptions.nonew.abilist b/libcxx/lib/abi/powerpc-ibm-aix.libcxxabi.v1.stable.exceptions.nonew.abilist
index 99cde72885cf2..f1244d12570c1 100644
--- a/libcxx/lib/abi/powerpc-ibm-aix.libcxxabi.v1.stable.exceptions.nonew.abilist
+++ b/libcxx/lib/abi/powerpc-ibm-aix.libcxxabi.v1.stable.exceptions.nonew.abilist
@@ -677,6 +677,7 @@
 {'import_export': 'EXP', 'is_defined': True, 'name': '_ZNSt3__16__clocEv', 'storage_mapping_class': 'DS', 'type': 'FUNC'}
 {'import_export': 'EXP', 'is_defined': True, 'name': '_ZNSt3__16__itoa8__u32toaEjPc', 'storage_mapping_class': 'DS', 'type': 'FUNC'}
 {'import_export': 'EXP', 'is_defined': True, 'name': '_ZNSt3__16__itoa8__u64toaEyPc', 'storage_mapping_class': 'DS', 'type': 'FUNC'}
+{'import_export': 'EXP', 'is_defined': True, 'name': '_ZNSt3__16__math25__lgamma_thread_safe_implEd', 'storage_mapping_class': 'DS', 'type': 'FUNC'}
 {'import_export': 'EXP', 'is_defined': True, 'name': '_ZNSt3__16chrono12steady_clock3nowEv', 'storage_mapping_class': 'DS', 'type': 'FUNC'}
 {'import_export': 'EXP', 'is_defined': True, 'name': '_ZNSt3__16chrono12system_clock11from_time_tEi', 'storage_mapping_class': 'DS', 'type': 'FUNC'}
 {'import_export': 'EXP', 'is_defined': True, 'name': '_ZNSt3__16chrono12system_clock3nowEv', 'storage_mapping_class': 'DS', 'type': 'FUNC'}
diff --git a/libcxx/lib/abi/powerpc64-ibm-aix.libcxxabi.v1.stable.exceptions.nonew.abilist b/libcxx/lib/abi/powerpc64-ibm-aix.libcxxabi.v1.stable.exceptions.nonew.abilist
index 577d6cf759a77..af16461b1cd78 100644
--- a/libcxx/lib/abi/powerpc64-ibm-aix.libcxxabi.v1.stable.exceptions.nonew.abilist
+++ b/libcxx/lib/abi/powerpc64-ibm-aix.libcxxabi.v1.stable.exceptions.nonew.abilist
@@ -677,6 +677,7 @@
 {'import_export': 'EXP', 'is_defined': True, 'name': '_ZNSt3__16__clocEv', 'storage_mapping_class': 'DS', 'type': 'FUNC'}
 {'import_export': 'EXP', 'is_defined': True, 'name': '_ZNSt3__16__itoa8__u32toaEjPc', 'storage_mapping_class': 'DS', 'type': 'FUNC'}
 {'import_export': 'EXP', 'is_defined': True, 'name': '_ZNSt3__16__itoa8__u64toaEmPc', 'storage_mapping_class': 'DS', 'type': 'FUNC'}
+{'import_export': 'EXP', 'is_defined': True, 'name': '_ZNSt3__16__math25__lgamma_thread_safe_implEd', 'storage_mapping_class': 'DS', 'type': 'FUNC'}
 {'import_export': 'EXP', 'is_defined': True, 'name': '_ZNSt3__16chrono12steady_clock3nowEv', 'storage_mapping_class': 'DS', 'type': 'FUNC'}
 {'import_export': 'EXP', 'is_defined': True, 'name': '_ZNSt3__16chrono12system_clock11from_time_tEl', 'storage_mapping_class': 'DS', 'type': 'FUNC'}
 {'import_export': 'EXP', 'is_defined': True, 'name': '_ZNSt3__16chrono12system_clock3nowEv', 'storage_mapping_class': 'DS', 'type': 'FUNC'}
diff --git a/libcxx/lib/abi/x86_64-apple-darwin.libcxxabi.v1.stable.exceptions.nonew.abilist b/libcxx/lib/abi/x86_64-apple-darwin.libcxxabi.v1.stable.exceptions.nonew.abilist
index 5173a1a76b81a..5361d12bbd0c8 100644
--- a/libcxx/lib/abi/x86_64-apple-darwin.libcxxabi.v1.stable.exceptions.nonew.abilist
+++ b/libcxx/lib/abi/x86_64-apple-darwin.libcxxabi.v1.stable.exceptions.nonew.abilist
@@ -1691,6 +1691,7 @@
 {'is_defined': True, 'name': '__ZNSt3__15wcoutE', 'size': 0, 'type': 'OBJECT'}
 {'is_defined': True, 'name': '__ZNSt3__16__itoa8__u32toaEjPc', 'type': 'FUNC'}
 {'is_defined': True, 'name': '__ZNSt3__16__itoa8__u64toaEyPc', 'type': 'FUNC'}
+{'is_defined': True, 'name': '__ZNSt3__16__math25__lgamma_thread_safe_implEd', 'type': 'FUNC'}
 {'is_defined': True, 'name': '__ZNSt3__16__sortIRNS_6__lessIaaEEPaEEvT0_S5_T_', 'type': 'FUNC'}
 {'is_defined': True, 'name': '__ZNSt3__16__sortIRNS_6__lessIccEEPcEEvT0_S5_T_', 'type': 'FUNC'}
 {'is_defined': True, 'name': '__ZNSt3__16__sortIRNS_6__lessIddEEPdEEvT0_S5_T_', 'type': 'FUNC'}
diff --git a/libcxx/lib/abi/x86_64-linux-android21.libcxxabi.v1.stable.exceptions.nonew.abilist b/libcxx/lib/abi/x86_64-linux-android21.libcxxabi.v1.stable.exceptions.nonew.abilist
index 1be7d8a2ac20b..e8a420e4e9122 100644
--- a/libcxx/lib/abi/x86_64-linux-android21.libcxxabi.v1.stable.exceptions.nonew.abilist
+++ b/libcxx/lib/abi/x86_64-linux-android21.libcxxabi.v1.stable.exceptions.nonew.abilist
@@ -1329,6 +1329,7 @@
 {'is_defined': True, 'name': '_ZNSt6__ndk16__clocEv', 'type': 'FUNC'}
 {'is_defined': True, 'name': '_ZNSt6__ndk16__itoa8__u32toaEjPc', 'type': 'FUNC'}
 {'is_defined': True, 'name': '_ZNSt6__ndk16__itoa8__u64toaEmPc', 'type': 'FUNC'}
+{'is_defined': True, 'name': '_ZNSt6__ndk16__math25__lgamma_thread_safe_implEd', 'type': 'FUNC'}
 {'is_defined': True, 'name': '_ZNSt6__ndk16__sortIRNS_6__lessIaaEEPaEEvT0_S5_T_', 'type': 'FUNC'}
 {'is_defined': True, 'name': '_ZNSt6__ndk16__sortIRNS_6__lessIccEEPcEEvT0_S5_T_', 'type': 'FUNC'}
 {'is_defined': True, 'name': '_ZNSt6__ndk16__sortIRNS_6__lessIddEEPdEEvT0_S5_T_', 'type': 'FUNC'}
diff --git a/libcxx/lib/abi/x86_64-unknown-freebsd.libcxxabi.v1.stable.exceptions.nonew.abilist b/libcxx/lib/abi/x86_64-unknown-freebsd.libcxxabi.v1.stable.exceptions.nonew.abilist
index 40ae625d3bd69..bd2208f403d5b 100644
--- a/libcxx/lib/abi/x86_64-unknown-freebsd.libcxxabi.v1.stable.exceptions.nonew.abilist
+++ b/libcxx/lib/abi/x86_64-unknown-freebsd.libcxxabi.v1.stable.exceptions.nonew.abilist
@@ -1342,6 +1342,7 @@
 {'is_defined': True, 'name': '_ZNSt3__15wcoutE', 'size': 384, 'type': 'OBJECT'}
 {'is_defined': True, 'name': '_ZNSt3__16__itoa8__u32toaEjPc', 'type': 'FUNC'}
 {'is_defined': True, 'name': '_ZNSt3__16__itoa8__u64toaEmPc', 'type': 'FUNC'}
+{'is_defined': True, 'name': '_ZNSt3__16__math25__lgamma_thread_safe_implEd', 'type': 'FUNC'}
 {'is_defined': True, 'name': '_ZNSt3__16__sortIRNS_6__lessIaaEEPaEEvT0_S5_T_', 'type': 'FUNC'}
 {'is_defined': True, 'name': '_ZNSt3__16__sortIRNS_6__lessIccEEPcEEvT0_S5_T_', 'type': 'FUNC'}
 {'is_defined': True, 'name': '_ZNSt3__16__sortIRNS_6__lessIddEEPdEEvT0_S5_T_', 'type': 'FUNC'}
diff --git a/libcxx/lib/abi/x86_64-unknown-linux-gnu.libcxxabi.v1.stable.exceptions.nonew.abilist b/libcxx/lib/abi/x86_64-unknown-linux-gnu.libcxxabi.v1.stable.exceptions.nonew.abilist
index 90166073b135f..bd2303afa3222 100644
--- a/libcxx/lib/abi/x86_64-unknown-linux-gnu.libcxxabi.v1.stable.exceptions.nonew.abilist
+++ b/libcxx/lib/abi/x86_64-unknown-linux-gnu.libcxxabi.v1.stable.exceptions.nonew.abilist
@@ -1341,6 +1341,7 @@
 {'is_defined': True, 'name': '_ZNSt3__16__clocEv', 'type': 'FUNC'}
 {'is_defined': True, 'name': '_ZNSt3__16__itoa8__u32toaEjPc', 'type': 'FUNC'}
 {'is_defined': True, 'name': '_ZNSt3__16__itoa8__u64toaEmPc', 'type': 'FUNC'}
+{'is_defined': True, 'name': '_ZNSt3__16__math25__lgamma_thread_safe_implEd', 'type': 'FUNC'}
 {'is_defined': True, 'name': '_ZNSt3__16__sortIRNS_6__lessIaaEEPaEEvT0_S5_T_', 'type': 'FUNC'}
 {'is_defined': True, 'name': '_ZNSt3__16__sortIRNS_6__lessIccEEPcEEvT0_S5_T_', 'type': 'FUNC'}
 {'is_defined': True, 'name': '_ZNSt3__16__sortIRNS_6__lessIddEEPdEEvT0_S5_T_', 'type': 'FUNC'}
diff --git a/libcxx/lib/abi/x86_64-unknown-linux-gnu.libcxxabi.v1.stable.noexceptions.nonew.abilist b/libcxx/lib/abi/x86_64-unknown-linux-gnu.libcxxabi.v1.stable.noexceptions.nonew.abilist
index 5855c17cf11ed..eb7566ffe951c 100644
--- a/libcxx/lib/abi/x86_64-unknown-linux-gnu.libcxxabi.v1.stable.noexceptions.nonew.abilist
+++ b/libcxx/lib/abi/x86_64-unknown-linux-gnu.libcxxabi.v1.stable.noexceptions.nonew.abilist
@@ -1312,6 +1312,7 @@
 {'is_defined': True, 'name': '_ZNSt3__16__clocEv', 'type': 'FUNC'}
 {'is_defined': True, 'name': '_ZNSt3__16__itoa8__u32toaEjPc', 'type': 'FUNC'}
 {'is_defined': True, 'name': '_ZNSt3__16__itoa8__u64toaEmPc', 'type': 'FUNC'}
+{'is_defined': True, 'name': '_ZNSt3__16__math25__lgamma_thread_safe_implEd', 'type': 'FUNC'}
 {'is_defined': True, 'name': '_ZNSt3__16__sortIRNS_6__lessIaaEEPaEEvT0_S5_T_', 'type': 'FUNC'}
 {'is_defined': True, 'name': '_ZNSt3__16__sortIRNS_6__lessIccEEPcEEvT0_S5_T_', 'type': 'FUNC'}
 {'is_defined': True, 'name': '_ZNSt3__16__sortIRNS_6__lessIddEEPdEEvT0_S5_T_', 'type': 'FUNC'}
diff --git a/libcxx/src/CMakeLists.txt b/libcxx/src/CMakeLists.txt
index f59fe0e08fccb..16e9a2e163dad 100644
--- a/libcxx/src/CMakeLists.txt
+++ b/libcxx/src/CMakeLists.txt
@@ -30,6 +30,7 @@ set(LIBCXX_SOURCES
   include/ryu/ryu.h
   include/to_chars_floating_point.h
   include/from_chars_floating_point.h
+  math.cpp
   memory.cpp
   memory_resource.cpp
   new_handler.cpp
diff --git a/libcxx/src/math.cpp b/libcxx/src/math.cpp
new file mode 100644
index 0000000000000..2b33f919a4d70
--- /dev/null
+++ b/libcxx/src/math.cpp
@@ -0,0 +1,26 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifdef __APPLE__
+#  define _REENTRANT
+#endif
+
+#include <cmath>
+#include <math.h> // for lgamma_r
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+namespace __math {
+
+_LIBCPP_EXPORTED_FROM_ABI __lgamma_result __lgamma_thread_safe_impl(double __d) noexcept {
+  int __sign;
+  double __result = ::lgamma_r(__d, &__sign);
+  return __lgamma_result{__result, __sign};
+}
+
+} // namespace __math
+_LIBCPP_END_NAMESPACE_STD