--- libmalloc/libmalloc-521.120.7/include/malloc/_malloc.h
+++ libmalloc/libmalloc-646.0.13/include/malloc/_malloc.h
@@ -34,10 +34,10 @@
 #include <sys/cdefs.h>
 #if __has_include(<sys/_types/_size_t.h>)
 #include <sys/_types/_size_t.h>
-#elif __has_include(<_liblibc/_size_t.h>)
-#include <_liblibc/_size_t.h>
 #else
-#error "Missing definition of size_t!"
+#define __need_size_t
+#include <stddef.h>
+#undef __need_size_t
 #endif
 
 #if !defined(_ANSI_SOURCE) && (!defined(_POSIX_C_SOURCE) || defined(_DARWIN_C_SOURCE))
@@ -51,20 +51,20 @@
 
 __BEGIN_DECLS
 
-void *malloc(size_t __size) __result_use_check __alloc_size(1) _MALLOC_TYPED(malloc_type_malloc, 1);
-void *calloc(size_t __count, size_t __size) __result_use_check __alloc_size(1,2) _MALLOC_TYPED(malloc_type_calloc, 2);
+void * __sized_by_or_null(__size) malloc(size_t __size) __result_use_check __alloc_size(1) _MALLOC_TYPED(malloc_type_malloc, 1);
+void * __sized_by_or_null(__count * __size) calloc(size_t __count, size_t __size) __result_use_check __alloc_size(1,2) _MALLOC_TYPED(malloc_type_calloc, 2);
 void  free(void * __unsafe_indexable);
-void *realloc(void * __unsafe_indexable __ptr, size_t __size) __result_use_check __alloc_size(2) _MALLOC_TYPED(malloc_type_realloc, 2);
-void *reallocf(void * __unsafe_indexable __ptr, size_t __size) __result_use_check __alloc_size(2);
+void * __sized_by_or_null(__size) realloc(void * __unsafe_indexable __ptr, size_t __size) __result_use_check __alloc_size(2) _MALLOC_TYPED(malloc_type_realloc, 2);
+void * __sized_by_or_null(__size) reallocf(void * __unsafe_indexable __ptr, size_t __size) __result_use_check __alloc_size(2);
 #if !defined(_ANSI_SOURCE) && (!defined(_POSIX_C_SOURCE) || defined(_DARWIN_C_SOURCE))
-void *valloc(size_t) __alloc_size(1) _MALLOC_TYPED(malloc_type_valloc, 1);
+void * __sized_by_or_null(__size) valloc(size_t __size) __result_use_check __alloc_size(1) _MALLOC_TYPED(malloc_type_valloc, 1);
 #endif /* !defined(_ANSI_SOURCE) && (!defined(_POSIX_C_SOURCE) || defined(_DARWIN_C_SOURCE)) */
 #if (defined(__DARWIN_C_LEVEL) && defined(__DARWIN_C_FULL) && __DARWIN_C_LEVEL >= __DARWIN_C_FULL) || \
     (defined(__STDC_VERSION__) && __STDC_VERSION__ >= 201112L) || \
     (defined(__cplusplus) && __cplusplus >= 201703L)
-void *aligned_alloc(size_t __alignment, size_t __size) __result_use_check __alloc_align(1) __alloc_size(2) _MALLOC_TYPED(malloc_type_aligned_alloc, 2) __OSX_AVAILABLE(10.15) __IOS_AVAILABLE(13.0) __TVOS_AVAILABLE(13.0) __WATCHOS_AVAILABLE(6.0);
+void * __sized_by_or_null(__size) aligned_alloc(size_t __alignment, size_t __size) __result_use_check __alloc_align(1) __alloc_size(2) _MALLOC_TYPED(malloc_type_aligned_alloc, 2) __OSX_AVAILABLE(10.15) __IOS_AVAILABLE(13.0) __TVOS_AVAILABLE(13.0) __WATCHOS_AVAILABLE(6.0);
 #endif
-/* rdar://75598414 (Support __counted_by_or_null) */
+/* rdar://120689514 */
 int   posix_memalign(void * __unsafe_indexable *__memptr, size_t __alignment, size_t __size) _MALLOC_TYPED(malloc_type_posix_memalign, 3)  __OSX_AVAILABLE_STARTING(__MAC_10_6, __IPHONE_3_0);
 
 __END_DECLS