Index: include/__config
===================================================================
--- include/__config
+++ include/__config
@@ -597,6 +597,11 @@
 
 #define _LIBCPP_HAS_NO_ASAN
 
+// Allow for build-time disabling of unsigned integer sanitization
+#ifndef _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK
+#define _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK __attribute((no_sanitize("unsigned integer")))
+#endif 
+
 #endif // __clang__ || __GNUC__ || _MSC_VER || __IBMCPP__
 
 #ifndef _LIBCPP_HAS_NO_NOEXCEPT
@@ -826,6 +831,10 @@
 #define _LIBCPP_HAS_NO_ATOMIC_HEADER
 #endif
 
+#ifndef _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK
+#define _LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK
+#endif 
+
 #endif // __cplusplus
 
 #endif // _LIBCPP_CONFIG
Index: include/memory
===================================================================
--- include/memory
+++ include/memory
@@ -3194,7 +3194,7 @@
 // murmur2
 template <class _Size>
 _Size
-__murmur2_or_cityhash<_Size, 32>::operator()(const void* __key, _Size __len)
+_LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK __murmur2_or_cityhash<_Size, 32>::operator()(const void* __key, _Size __len)
 {
     const _Size __m = 0x5bd1e995;
     const _Size __r = 24;
@@ -3344,7 +3344,7 @@
 // cityhash64
 template <class _Size>
 _Size
-__murmur2_or_cityhash<_Size, 64>::operator()(const void* __key, _Size __len)
+_LIBCPP_DISABLE_UBSAN_UNSIGNED_INTEGER_CHECK __murmur2_or_cityhash<_Size, 64>::operator()(const void* __key, _Size __len)
 {
   const char* __s = static_cast<const char*>(__key);
   if (__len <= 32) {