--- libmalloc/libmalloc-792.1.1/include/malloc/_malloc.h
+++ libmalloc/libmalloc-521.100.59/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
-#define __need_size_t
-#include <stddef.h>
-#undef __need_size_t
+#error "Missing definition of size_t!"
 #endif
 
 #if !defined(_ANSI_SOURCE) && (!defined(_POSIX_C_SOURCE) || defined(_DARWIN_C_SOURCE))
@@ -51,91 +51,22 @@
 
 __BEGIN_DECLS
 
-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 *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  free(void * __unsafe_indexable);
-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 *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);
 #if !defined(_ANSI_SOURCE) && (!defined(_POSIX_C_SOURCE) || defined(_DARWIN_C_SOURCE))
-void * __sized_by_or_null(__size) reallocf(void * __unsafe_indexable __ptr, size_t __size) __result_use_check __alloc_size(2);
-void * __sized_by_or_null(__size) valloc(size_t __size) __result_use_check __alloc_size(1) _MALLOC_TYPED(malloc_type_valloc, 1);
+void *valloc(size_t) __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 * __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);
+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);
 #endif
-/* rdar://120689514 */
+/* rdar://75598414 (Support __counted_by_or_null) */
 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);
 
-#if defined(_MALLOC_TYPE_MALLOC_IS_BACKDEPLOYING) && _MALLOC_TYPE_MALLOC_IS_BACKDEPLOYING
-static void * __sized_by_or_null(size) __attribute__((always_inline)) malloc_type_malloc_backdeploy(size_t size, malloc_type_id_t type_id) __result_use_check __alloc_size(1) {
-	__attribute__((weak_import)) void * __sized_by_or_null(size) malloc_type_malloc(size_t size, malloc_type_id_t type_id) __result_use_check __alloc_size(1);
-	__auto_type func = malloc;
-	if (malloc_type_malloc) {
-		return malloc_type_malloc(size, type_id);
-	}
-	return func(size);
-}
-
-static void * __sized_by_or_null(count * size) __attribute__((always_inline)) malloc_type_calloc_backdeploy(size_t count, size_t size, malloc_type_id_t type_id) __result_use_check __alloc_size(1,2) {
-	__attribute__((weak_import)) void * __sized_by_or_null(count * size) malloc_type_calloc(size_t count, size_t size, malloc_type_id_t type_id) __result_use_check __alloc_size(1,2);
-	__auto_type func = calloc;
-	if (malloc_type_calloc) {
-		return malloc_type_calloc(count, size, type_id);
-	}
-	return func(count, size);
-}
-
-static void __attribute__((always_inline)) malloc_type_free_backdeploy(void * __unsafe_indexable ptr, malloc_type_id_t type_id) {
-	__attribute__((weak_import)) void  malloc_type_free(void * __unsafe_indexable ptr, malloc_type_id_t type_id);
-	__auto_type func = free;
-	if (malloc_type_free) {
-		malloc_type_free(ptr, type_id);
-	} else {
-		func(ptr);
-	}
-}
-
-static void * __sized_by_or_null(size) __attribute__((always_inline)) malloc_type_realloc_backdeploy(void * __unsafe_indexable ptr, size_t size, malloc_type_id_t type_id) __result_use_check __alloc_size(2) {
-	__attribute__((weak_import)) void * __sized_by_or_null(size) malloc_type_realloc(void * __unsafe_indexable ptr, size_t size, malloc_type_id_t type_id) __result_use_check __alloc_size(2);
-	__auto_type func = realloc;
-	if (malloc_type_realloc) {
-		return malloc_type_realloc(ptr, size, type_id);
-	}
-	return func(ptr, size);
-}
-
-static void * __sized_by_or_null(size) __attribute__((always_inline)) malloc_type_valloc_backdeploy(size_t size, malloc_type_id_t type_id) __result_use_check __alloc_size(1) {
-	__attribute__((weak_import)) void * __sized_by_or_null(size) malloc_type_valloc(size_t size, malloc_type_id_t type_id) __result_use_check __alloc_size(1);
-	__auto_type func = valloc;
-	if (malloc_type_valloc) {
-		return malloc_type_valloc(size, type_id);
-	}
-	return func(size);
-}
-
-#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)
-static void * __sized_by_or_null(size) __attribute__((always_inline)) malloc_type_aligned_alloc_backdeploy(size_t alignment, size_t size, malloc_type_id_t type_id) __result_use_check __alloc_align(1) __alloc_size(2) {
-	__attribute__((weak_import)) void * __sized_by_or_null(size) malloc_type_aligned_alloc(size_t alignment, size_t size, malloc_type_id_t type_id) __result_use_check __alloc_align(1) __alloc_size(2);
-	__auto_type func = aligned_alloc;
-	if (malloc_type_aligned_alloc) {
-		return malloc_type_aligned_alloc(alignment, size, type_id);
-	}
-	return func(alignment, size);
-}
-#endif
-
-static int __attribute__((always_inline)) malloc_type_posix_memalign_backdeploy(void * __unsafe_indexable *memptr, size_t alignment, size_t size, malloc_type_id_t type_id) {
-	__attribute__((weak_import)) int malloc_type_posix_memalign(void * __unsafe_indexable *memptr, size_t alignment, size_t size, malloc_type_id_t type_id);
-	__auto_type func = posix_memalign;
-	if (malloc_type_posix_memalign) {
-		return malloc_type_posix_memalign(memptr, alignment, size, type_id);
-	}
-	return func(memptr, alignment, size);
-}
-#endif
 __END_DECLS
 
 #endif /* _MALLOC_UNDERSCORE_MALLOC_H_ */