diff --git a/libc/include/android/api-level.h b/libc/include/android/api-level.h
index 1bde3a5..c9536c1 100644
--- a/libc/include/android/api-level.h
+++ b/libc/include/android/api-level.h
@@ -189,7 +189,11 @@
  *
  * Available since API level 24.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(24)
 int android_get_application_target_sdk_version() __INTRODUCED_IN(24);
+#endif /* __BIONIC_AVAILABILITY_GUARD(24) */
+
 
 #if __ANDROID_API__ < 29
 
diff --git a/libc/include/android/crash_detail.h b/libc/include/android/crash_detail.h
index 490ec8c..fd1312a 100644
--- a/libc/include/android/crash_detail.h
+++ b/libc/include/android/crash_detail.h
@@ -80,6 +80,8 @@
  *
  * \return a handle to the extra crash detail.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(35)
 crash_detail_t* _Nullable android_crash_detail_register(
     const void* _Nonnull name, size_t name_size, const void* _Nullable data, size_t data_size) __INTRODUCED_IN(35);
 
@@ -123,5 +125,7 @@
  * \param name_size number of bytes of the buffer pointed to by name
  */
 void android_crash_detail_replace_name(crash_detail_t* _Nonnull crash_detail, const void* _Nonnull name, size_t name_size) __INTRODUCED_IN(35);
+#endif /* __BIONIC_AVAILABILITY_GUARD(35) */
+
 
 __END_DECLS
diff --git a/libc/include/android/fdsan.h b/libc/include/android/fdsan.h
index fd0a63f..a04fc7e 100644
--- a/libc/include/android/fdsan.h
+++ b/libc/include/android/fdsan.h
@@ -135,6 +135,8 @@
 /*
  * Create an owner tag with the specified type and least significant 56 bits of tag.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(29)
 uint64_t android_fdsan_create_owner_tag(enum android_fdsan_owner_type type, uint64_t tag) __INTRODUCED_IN(29) __attribute__((__weak__));
 
 /*
@@ -169,6 +171,8 @@
  * Get an owner tag's value, with the type masked off.
  */
 uint64_t android_fdsan_get_tag_value(uint64_t tag) __INTRODUCED_IN(29);
+#endif /* __BIONIC_AVAILABILITY_GUARD(29) */
+
 
 enum android_fdsan_error_level {
   // No errors.
@@ -187,6 +191,8 @@
 /*
  * Get the error level.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(29)
 enum android_fdsan_error_level android_fdsan_get_error_level() __INTRODUCED_IN(29) __attribute__((__weak__));
 
 /*
@@ -204,9 +210,15 @@
  * (e.g. postfork).
  */
 enum android_fdsan_error_level android_fdsan_set_error_level(enum android_fdsan_error_level new_level) __INTRODUCED_IN(29) __attribute__((__weak__));
+#endif /* __BIONIC_AVAILABILITY_GUARD(29) */
+
 
 /*
  * Set the error level to the global setting if available, or a default value.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(30)
 enum android_fdsan_error_level android_fdsan_set_error_level_from_property(enum android_fdsan_error_level default_level) __INTRODUCED_IN(30) __attribute__((__weak__));
+#endif /* __BIONIC_AVAILABILITY_GUARD(30) */
+
 __END_DECLS
diff --git a/libc/include/arpa/nameser.h b/libc/include/arpa/nameser.h
index 7f8b9ba..3e0025e 100644
--- a/libc/include/arpa/nameser.h
+++ b/libc/include/arpa/nameser.h
@@ -548,6 +548,8 @@
 #define ns_sprintrrf __ns_sprintrrf
 #endif
 
+
+#if __BIONIC_AVAILABILITY_GUARD(22)
 int ns_msg_getflag(ns_msg __handle, int __flag) __INTRODUCED_IN(22);
 uint16_t ns_get16(const u_char* _Nonnull __src) __INTRODUCED_IN(22);
 uint32_t ns_get32(const u_char* _Nonnull __src) __INTRODUCED_IN(22);
@@ -571,6 +573,8 @@
 
 int ns_makecanon(const char* _Nonnull __src, char* _Nonnull __dst, size_t __dst_size) __INTRODUCED_IN(22);
 int ns_samename(const char* _Nonnull __lhs, const char* _Nonnull __rhs) __INTRODUCED_IN(22);
+#endif /* __BIONIC_AVAILABILITY_GUARD(22) */
+
 
 __END_DECLS
 
diff --git a/libc/include/bits/fortify/poll.h b/libc/include/bits/fortify/poll.h
index f2e27d7..1b4a5bf 100644
--- a/libc/include/bits/fortify/poll.h
+++ b/libc/include/bits/fortify/poll.h
@@ -30,9 +30,17 @@
 #error "Never include this file directly; instead, include <poll.h>"
 #endif
 
+
+#if __BIONIC_AVAILABILITY_GUARD(23)
 int __poll_chk(struct pollfd* _Nullable, nfds_t, int, size_t) __INTRODUCED_IN(23);
 int __ppoll_chk(struct pollfd* _Nullable, nfds_t, const struct timespec* _Nullable, const sigset_t* _Nullable, size_t) __INTRODUCED_IN(23);
+#endif /* __BIONIC_AVAILABILITY_GUARD(23) */
+
+
+#if __BIONIC_AVAILABILITY_GUARD(28)
 int __ppoll64_chk(struct pollfd* _Nullable, nfds_t, const struct timespec* _Nullable, const sigset64_t* _Nullable, size_t) __INTRODUCED_IN(28);
+#endif /* __BIONIC_AVAILABILITY_GUARD(28) */
+
 
 #if defined(__BIONIC_FORTIFY)
 #define __bos_fd_count_trivially_safe(bos_val, fds, fd_count)              \
diff --git a/libc/include/bits/fortify/socket.h b/libc/include/bits/fortify/socket.h
index 1c3605b..bd626f9 100644
--- a/libc/include/bits/fortify/socket.h
+++ b/libc/include/bits/fortify/socket.h
@@ -30,7 +30,11 @@
 #error "Never include this file directly; instead, include <sys/socket.h>"
 #endif
 
+
+#if __BIONIC_AVAILABILITY_GUARD(26)
 ssize_t __sendto_chk(int, const void* _Nonnull, size_t, size_t, int, const struct sockaddr* _Nullable, socklen_t) __INTRODUCED_IN(26);
+#endif /* __BIONIC_AVAILABILITY_GUARD(26) */
+
 ssize_t __recvfrom_chk(int, void* _Nullable, size_t, size_t, int, struct sockaddr* _Nullable, socklen_t* _Nullable);
 
 #if defined(__BIONIC_FORTIFY)
diff --git a/libc/include/bits/fortify/stdio.h b/libc/include/bits/fortify/stdio.h
index e4607e0..f9faeba 100644
--- a/libc/include/bits/fortify/stdio.h
+++ b/libc/include/bits/fortify/stdio.h
@@ -31,8 +31,12 @@
 #endif
 
 char* _Nullable __fgets_chk(char* _Nonnull, int, FILE* _Nonnull, size_t);
+
+#if __BIONIC_AVAILABILITY_GUARD(24)
 size_t __fread_chk(void* _Nonnull, size_t, size_t, FILE* _Nonnull, size_t) __INTRODUCED_IN(24);
 size_t __fwrite_chk(const void* _Nonnull, size_t, size_t, FILE* _Nonnull, size_t) __INTRODUCED_IN(24);
+#endif /* __BIONIC_AVAILABILITY_GUARD(24) */
+
 
 #if defined(__BIONIC_FORTIFY) && !defined(__BIONIC_NO_STDIO_FORTIFY)
 
diff --git a/libc/include/bits/fortify/string.h b/libc/include/bits/fortify/string.h
index 041967b..6f0ee4a 100644
--- a/libc/include/bits/fortify/string.h
+++ b/libc/include/bits/fortify/string.h
@@ -30,8 +30,12 @@
 #error "Never include this file directly; instead, include <string.h>"
 #endif
 
+
+#if __BIONIC_AVAILABILITY_GUARD(23)
 void* _Nullable __memchr_chk(const void* _Nonnull, int, size_t, size_t) __INTRODUCED_IN(23);
 void* _Nullable __memrchr_chk(const void* _Nonnull, int, size_t, size_t) __INTRODUCED_IN(23);
+#endif /* __BIONIC_AVAILABILITY_GUARD(23) */
+
 char* _Nonnull __stpncpy_chk2(char* _Nonnull, const char* _Nonnull, size_t, size_t, size_t);
 char* _Nonnull __strncpy_chk2(char* _Nonnull, const char* _Nonnull, size_t, size_t, size_t);
 size_t __strlcpy_chk(char* _Nonnull, const char* _Nonnull, size_t, size_t);
diff --git a/libc/include/bits/fortify/unistd.h b/libc/include/bits/fortify/unistd.h
index 7eda1a6..9acb942 100644
--- a/libc/include/bits/fortify/unistd.h
+++ b/libc/include/bits/fortify/unistd.h
@@ -29,24 +29,52 @@
 #error "Never include this file directly; instead, include <unistd.h>"
 #endif
 
-char* _Nullable __getcwd_chk(char* _Nullable, size_t, size_t) __INTRODUCED_IN(24);
 
+#if __BIONIC_AVAILABILITY_GUARD(24)
+char* _Nullable __getcwd_chk(char* _Nullable, size_t, size_t) __INTRODUCED_IN(24);
+#endif /* __BIONIC_AVAILABILITY_GUARD(24) */
+
+
+
+#if __BIONIC_AVAILABILITY_GUARD(23)
 ssize_t __pread_chk(int, void* _Nonnull, size_t, off_t, size_t) __INTRODUCED_IN(23);
+#endif /* __BIONIC_AVAILABILITY_GUARD(23) */
+
 ssize_t __pread_real(int, void* _Nonnull, size_t, off_t) __RENAME(pread);
 
+
+#if __BIONIC_AVAILABILITY_GUARD(23)
 ssize_t __pread64_chk(int, void* _Nonnull, size_t, off64_t, size_t) __INTRODUCED_IN(23);
+#endif /* __BIONIC_AVAILABILITY_GUARD(23) */
+
 ssize_t __pread64_real(int, void* _Nonnull, size_t, off64_t) __RENAME(pread64);
 
+
+#if __BIONIC_AVAILABILITY_GUARD(24)
 ssize_t __pwrite_chk(int, const void* _Nonnull, size_t, off_t, size_t) __INTRODUCED_IN(24);
+#endif /* __BIONIC_AVAILABILITY_GUARD(24) */
+
 ssize_t __pwrite_real(int, const void* _Nonnull, size_t, off_t) __RENAME(pwrite);
 
+
+#if __BIONIC_AVAILABILITY_GUARD(24)
 ssize_t __pwrite64_chk(int, const void* _Nonnull, size_t, off64_t, size_t) __INTRODUCED_IN(24);
+#endif /* __BIONIC_AVAILABILITY_GUARD(24) */
+
 ssize_t __pwrite64_real(int, const void* _Nonnull, size_t, off64_t) __RENAME(pwrite64);
 
 ssize_t __read_chk(int, void* __BIONIC_COMPLICATED_NULLNESS, size_t, size_t);
+
+#if __BIONIC_AVAILABILITY_GUARD(24)
 ssize_t __write_chk(int, const void* __BIONIC_COMPLICATED_NULLNESS, size_t, size_t) __INTRODUCED_IN(24);
+#endif /* __BIONIC_AVAILABILITY_GUARD(24) */
+
+
+#if __BIONIC_AVAILABILITY_GUARD(23)
 ssize_t __readlink_chk(const char* _Nonnull, char* _Nonnull, size_t, size_t) __INTRODUCED_IN(23);
 ssize_t __readlinkat_chk(int dirfd, const char* _Nonnull, char* _Nonnull, size_t, size_t) __INTRODUCED_IN(23);
+#endif /* __BIONIC_AVAILABILITY_GUARD(23) */
+
 
 #if defined(__BIONIC_FORTIFY)
 
diff --git a/libc/include/bits/getentropy.h b/libc/include/bits/getentropy.h
index 98d8879..c878470 100644
--- a/libc/include/bits/getentropy.h
+++ b/libc/include/bits/getentropy.h
@@ -48,6 +48,10 @@
  *
  * See also arc4random_buf() which is available in all API levels.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(28)
 __nodiscard int getentropy(void* _Nonnull __buffer, size_t __buffer_size) __INTRODUCED_IN(28);
+#endif /* __BIONIC_AVAILABILITY_GUARD(28) */
+
 
 __END_DECLS
diff --git a/libc/include/bits/lockf.h b/libc/include/bits/lockf.h
index 195b34a..8f922b9 100644
--- a/libc/include/bits/lockf.h
+++ b/libc/include/bits/lockf.h
@@ -56,6 +56,8 @@
  *
  * See also flock().
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(24)
 int lockf(int __fd, int __op, off_t __length) __RENAME_IF_FILE_OFFSET64(lockf64) __INTRODUCED_IN(24);
 
 /**
@@ -63,5 +65,7 @@
  * even from a 32-bit process without `_FILE_OFFSET_BITS=64`.
  */
 int lockf64(int __fd, int __op, off64_t __length) __INTRODUCED_IN(24);
+#endif /* __BIONIC_AVAILABILITY_GUARD(24) */
+
 
 __END_DECLS
diff --git a/libc/include/bits/strcasecmp.h b/libc/include/bits/strcasecmp.h
index be910ad..d76cec9 100644
--- a/libc/include/bits/strcasecmp.h
+++ b/libc/include/bits/strcasecmp.h
@@ -51,7 +51,11 @@
 /**
  * Like strcasecmp() but taking a `locale_t`.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(23)
 int strcasecmp_l(const char* _Nonnull __s1, const char* _Nonnull __s2, locale_t _Nonnull __l) __attribute_pure__ __INTRODUCED_IN(23);
+#endif /* __BIONIC_AVAILABILITY_GUARD(23) */
+
 
 /**
  * [strncasecmp(3)](https://man7.org/linux/man-pages/man3/strncasecmp.3.html) compares the first
@@ -66,6 +70,10 @@
 /**
  * Like strncasecmp() but taking a `locale_t`.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(23)
 int strncasecmp_l(const char* _Nonnull __s1, const char* _Nonnull __s2, size_t __n, locale_t _Nonnull __l) __attribute_pure__ __INTRODUCED_IN(23);
+#endif /* __BIONIC_AVAILABILITY_GUARD(23) */
+
 
 __END_DECLS
diff --git a/libc/include/bits/wctype.h b/libc/include/bits/wctype.h
index 13a4254..d0cffec 100644
--- a/libc/include/bits/wctype.h
+++ b/libc/include/bits/wctype.h
@@ -58,8 +58,12 @@
 int iswctype(wint_t __wc, wctype_t __type);
 
 typedef const void* wctrans_t;
+
+#if __BIONIC_AVAILABILITY_GUARD(26)
 wint_t towctrans(wint_t __wc, wctrans_t _Nonnull __transform) __INTRODUCED_IN(26);
 wctrans_t _Nullable wctrans(const char* _Nonnull __name) __INTRODUCED_IN(26);
+#endif /* __BIONIC_AVAILABILITY_GUARD(26) */
+
 
 __END_DECLS
 
diff --git a/libc/include/complex.h b/libc/include/complex.h
index f205abd..1115862 100644
--- a/libc/include/complex.h
+++ b/libc/include/complex.h
@@ -53,76 +53,190 @@
 
 /* 7.3.5 Trigonometric functions */
 /* 7.3.5.1 The cacos functions */
+
+#if __BIONIC_AVAILABILITY_GUARD(23)
 double complex cacos(double complex __z) __INTRODUCED_IN(23);
 float complex cacosf(float complex __z) __INTRODUCED_IN(23);
+#endif /* __BIONIC_AVAILABILITY_GUARD(23) */
+
+
+#if __BIONIC_AVAILABILITY_GUARD(26)
 long double complex cacosl(long double complex __z) __INTRODUCED_IN(26);
+#endif /* __BIONIC_AVAILABILITY_GUARD(26) */
+
 /* 7.3.5.2 The casin functions */
+
+#if __BIONIC_AVAILABILITY_GUARD(23)
 double complex casin(double complex __z) __INTRODUCED_IN(23);
 float complex casinf(float complex __z) __INTRODUCED_IN(23);
+#endif /* __BIONIC_AVAILABILITY_GUARD(23) */
+
+
+#if __BIONIC_AVAILABILITY_GUARD(26)
 long double complex casinl(long double complex __z) __INTRODUCED_IN(26);
+#endif /* __BIONIC_AVAILABILITY_GUARD(26) */
+
 /* 7.3.5.1 The catan functions */
+
+#if __BIONIC_AVAILABILITY_GUARD(23)
 double complex catan(double complex __z) __INTRODUCED_IN(23);
 float complex catanf(float complex __z) __INTRODUCED_IN(23);
+#endif /* __BIONIC_AVAILABILITY_GUARD(23) */
+
+
+#if __BIONIC_AVAILABILITY_GUARD(26)
 long double complex catanl(long double complex __z) __INTRODUCED_IN(26);
+#endif /* __BIONIC_AVAILABILITY_GUARD(26) */
+
 /* 7.3.5.1 The ccos functions */
+
+#if __BIONIC_AVAILABILITY_GUARD(23)
 double complex ccos(double complex __z) __INTRODUCED_IN(23);
 float complex ccosf(float complex __z) __INTRODUCED_IN(23);
+#endif /* __BIONIC_AVAILABILITY_GUARD(23) */
+
+
+#if __BIONIC_AVAILABILITY_GUARD(26)
 long double complex ccosl(long double complex __z) __INTRODUCED_IN(26);
+#endif /* __BIONIC_AVAILABILITY_GUARD(26) */
+
 /* 7.3.5.1 The csin functions */
+
+#if __BIONIC_AVAILABILITY_GUARD(23)
 double complex csin(double complex __z) __INTRODUCED_IN(23);
 float complex csinf(float complex __z) __INTRODUCED_IN(23);
+#endif /* __BIONIC_AVAILABILITY_GUARD(23) */
+
+
+#if __BIONIC_AVAILABILITY_GUARD(26)
 long double complex csinl(long double complex __z) __INTRODUCED_IN(26);
+#endif /* __BIONIC_AVAILABILITY_GUARD(26) */
+
 /* 7.3.5.1 The ctan functions */
+
+#if __BIONIC_AVAILABILITY_GUARD(23)
 double complex ctan(double complex __z) __INTRODUCED_IN(23);
 float complex ctanf(float complex __z) __INTRODUCED_IN(23);
+#endif /* __BIONIC_AVAILABILITY_GUARD(23) */
+
+
+#if __BIONIC_AVAILABILITY_GUARD(26)
 long double complex ctanl(long double complex __z) __INTRODUCED_IN(26);
+#endif /* __BIONIC_AVAILABILITY_GUARD(26) */
+
 
 /* 7.3.6 Hyperbolic functions */
 /* 7.3.6.1 The cacosh functions */
+
+#if __BIONIC_AVAILABILITY_GUARD(23)
 double complex cacosh(double complex __z) __INTRODUCED_IN(23);
 float complex cacoshf(float complex __z) __INTRODUCED_IN(23);
+#endif /* __BIONIC_AVAILABILITY_GUARD(23) */
+
+
+#if __BIONIC_AVAILABILITY_GUARD(26)
 long double complex cacoshl(long double complex __z) __INTRODUCED_IN(26);
+#endif /* __BIONIC_AVAILABILITY_GUARD(26) */
+
 /* 7.3.6.2 The casinh functions */
+
+#if __BIONIC_AVAILABILITY_GUARD(23)
 double complex casinh(double complex __z) __INTRODUCED_IN(23);
 float complex casinhf(float complex __z) __INTRODUCED_IN(23);
+#endif /* __BIONIC_AVAILABILITY_GUARD(23) */
+
+
+#if __BIONIC_AVAILABILITY_GUARD(26)
 long double complex casinhl(long double complex __z) __INTRODUCED_IN(26);
+#endif /* __BIONIC_AVAILABILITY_GUARD(26) */
+
 /* 7.3.6.3 The catanh functions */
+
+#if __BIONIC_AVAILABILITY_GUARD(23)
 double complex catanh(double complex __z) __INTRODUCED_IN(23);
 float complex catanhf(float complex __z) __INTRODUCED_IN(23);
+#endif /* __BIONIC_AVAILABILITY_GUARD(23) */
+
+
+#if __BIONIC_AVAILABILITY_GUARD(26)
 long double complex catanhl(long double complex __z) __INTRODUCED_IN(26);
+#endif /* __BIONIC_AVAILABILITY_GUARD(26) */
+
 /* 7.3.6.4 The ccosh functions */
+
+#if __BIONIC_AVAILABILITY_GUARD(23)
 double complex ccosh(double complex __z) __INTRODUCED_IN(23);
 float complex ccoshf(float complex __z) __INTRODUCED_IN(23);
+#endif /* __BIONIC_AVAILABILITY_GUARD(23) */
+
+
+#if __BIONIC_AVAILABILITY_GUARD(26)
 long double complex ccoshl(long double complex __z) __INTRODUCED_IN(26);
+#endif /* __BIONIC_AVAILABILITY_GUARD(26) */
+
 /* 7.3.6.5 The csinh functions */
+
+#if __BIONIC_AVAILABILITY_GUARD(23)
 double complex csinh(double complex __z) __INTRODUCED_IN(23);
 float complex csinhf(float complex __z) __INTRODUCED_IN(23);
+#endif /* __BIONIC_AVAILABILITY_GUARD(23) */
+
+
+#if __BIONIC_AVAILABILITY_GUARD(26)
 long double complex csinhl(long double complex __z) __INTRODUCED_IN(26);
+#endif /* __BIONIC_AVAILABILITY_GUARD(26) */
+
 /* 7.3.6.6 The ctanh functions */
+
+#if __BIONIC_AVAILABILITY_GUARD(23)
 double complex ctanh(double complex __z) __INTRODUCED_IN(23);
 float complex ctanhf(float complex __z) __INTRODUCED_IN(23);
+#endif /* __BIONIC_AVAILABILITY_GUARD(23) */
+
+
+#if __BIONIC_AVAILABILITY_GUARD(26)
 long double complex ctanhl(long double complex __z) __INTRODUCED_IN(26);
+#endif /* __BIONIC_AVAILABILITY_GUARD(26) */
+
 
 /* 7.3.7 Exponential and logarithmic functions */
 /* 7.3.7.1 The cexp functions */
+
+#if __BIONIC_AVAILABILITY_GUARD(23)
 double complex cexp(double complex __z) __INTRODUCED_IN(23);
 float complex cexpf(float complex __z) __INTRODUCED_IN(23);
+#endif /* __BIONIC_AVAILABILITY_GUARD(23) */
+
+
+#if __BIONIC_AVAILABILITY_GUARD(26)
 long double complex cexpl(long double complex __z) __INTRODUCED_IN(26);
 /* 7.3.7.2 The clog functions */
 double complex clog(double complex __z) __INTRODUCED_IN(26);
 float complex clogf(float complex __z) __INTRODUCED_IN(26);
 long double complex clogl(long double complex __z) __INTRODUCED_IN(26);
+#endif /* __BIONIC_AVAILABILITY_GUARD(26) */
+
 
 /* 7.3.8 Power and absolute-value functions */
 /* 7.3.8.1 The cabs functions */
+
+#if __BIONIC_AVAILABILITY_GUARD(23)
 double cabs(double complex __z) __INTRODUCED_IN(23);
 float cabsf(float complex __z) __INTRODUCED_IN(23);
 long double cabsl(long double complex __z) __INTRODUCED_IN(23);
+#endif /* __BIONIC_AVAILABILITY_GUARD(23) */
+
 /* 7.3.8.2 The cpow functions */
+
+#if __BIONIC_AVAILABILITY_GUARD(26)
 double complex cpow(double complex __x, double complex __z) __INTRODUCED_IN(26);
 float complex cpowf(float complex __x, float complex __z) __INTRODUCED_IN(26);
 long double complex cpowl(long double complex __x, long double complex __z) __INTRODUCED_IN(26);
+#endif /* __BIONIC_AVAILABILITY_GUARD(26) */
+
 /* 7.3.8.3 The csqrt functions */
+
+#if __BIONIC_AVAILABILITY_GUARD(23)
 double complex csqrt(double complex __z) __INTRODUCED_IN(23);
 float complex csqrtf(float complex __z) __INTRODUCED_IN(23);
 long double complex csqrtl(long double complex __z) __INTRODUCED_IN(23);
@@ -148,6 +262,8 @@
 double creal(double complex __z) __INTRODUCED_IN(23);
 float crealf(float complex __z) __INTRODUCED_IN(23);
 long double creall(long double complex __z) __INTRODUCED_IN(23);
+#endif /* __BIONIC_AVAILABILITY_GUARD(23) */
+
 
 __END_DECLS
 
diff --git a/libc/include/dirent.h b/libc/include/dirent.h
index 2695305..8058cfb 100644
--- a/libc/include/dirent.h
+++ b/libc/include/dirent.h
@@ -150,6 +150,8 @@
  *
  * Available since API level 23.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(23)
 void seekdir(DIR* _Nonnull __dir, long __location) __INTRODUCED_IN(23);
 
 /**
@@ -162,6 +164,8 @@
  * Available since API level 23.
  */
 long telldir(DIR* _Nonnull __dir) __INTRODUCED_IN(23);
+#endif /* __BIONIC_AVAILABILITY_GUARD(23) */
+
 
 /**
  * [dirfd(3)](https://man7.org/linux/man-pages/man3/dirfd.3.html)
@@ -222,6 +226,8 @@
  *
  * Available since API level 24.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(24)
 int scandirat64(int __dir_fd, const char* _Nonnull __path, struct dirent64* _Nonnull * _Nonnull * _Nonnull __name_list, int (* _Nullable __filter)(const struct dirent64* _Nonnull), int (* _Nullable __comparator)(const struct dirent64* _Nonnull * _Nonnull, const struct dirent64* _Nonnull * _Nonnull)) __INTRODUCED_IN(24);
 
 /**
@@ -238,6 +244,8 @@
  * Available since API level 24.
  */
 int scandirat(int __dir_fd, const char* _Nonnull __path, struct dirent* _Nonnull * _Nonnull * _Nonnull __name_list, int (* _Nullable __filter)(const struct dirent* _Nonnull), int (* _Nullable __comparator)(const struct dirent* _Nonnull * _Nonnull, const struct dirent* _Nonnull * _Nonnull)) __INTRODUCED_IN(24);
+#endif /* __BIONIC_AVAILABILITY_GUARD(24) */
+
 
 #endif
 
diff --git a/libc/include/dlfcn.h b/libc/include/dlfcn.h
index 1b0d11b..67759b8 100644
--- a/libc/include/dlfcn.h
+++ b/libc/include/dlfcn.h
@@ -117,7 +117,11 @@
  * Returns the address of the symbol on success, and returns NULL on failure,
  * in which case dlerror() can be used to retrieve the specific error.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(24)
 void* _Nullable dlvsym(void* __BIONIC_COMPLICATED_NULLNESS __handle, const char* _Nullable __symbol, const char* _Nullable __version) __INTRODUCED_IN(24);
+#endif /* __BIONIC_AVAILABILITY_GUARD(24) */
+
 
 /**
  * [dladdr(3)](https://man7.org/linux/man-pages/man3/dladdr.3.html)
diff --git a/libc/include/error.h b/libc/include/error.h
index 4d6a965..a9bdc24 100644
--- a/libc/include/error.h
+++ b/libc/include/error.h
@@ -37,9 +37,6 @@
 
 __BEGIN_DECLS
 
-// These cause issues with gnulib's polyfill
-// https://github.com/android/ndk/issues/2081
-#if __ANDROID_API__ >= 23
 /**
  * [error_print_progname(3)](https://man7.org/linux/man-pages/man3/error_print_progname.3.html) is
  * a function pointer that, if non-null, is called by error() instead of prefixing errors with the
@@ -47,10 +44,10 @@
  *
  * Available since API level 23.
  */
-extern void (* _Nullable error_print_progname)(void) __INTRODUCED_IN(23);
-#endif
 
-#if __ANDROID_API__ >= 23
+#if __BIONIC_AVAILABILITY_GUARD(23)
+extern void (* _Nullable error_print_progname)(void) __INTRODUCED_IN(23);
+
 /**
  * [error_message_count(3)](https://man7.org/linux/man-pages/man3/error_message_count.3.html) is
  * a global count of the number of calls to error() and error_at_line().
@@ -58,7 +55,6 @@
  * Available since API level 23.
  */
 extern unsigned int error_message_count __INTRODUCED_IN(23);
-#endif
 
 /**
  * [error_one_per_line(3)](https://man7.org/linux/man-pages/man3/error_one_per_line.3.html) is
@@ -87,5 +83,7 @@
  * Available since API level 23.
  */
 void error_at_line(int __status, int __errno, const char* _Nonnull __filename, unsigned int __line_number, const char* _Nonnull __fmt, ...) __printflike(5, 6) __INTRODUCED_IN(23);
+#endif /* __BIONIC_AVAILABILITY_GUARD(23) */
+
 
 __END_DECLS
diff --git a/libc/include/execinfo.h b/libc/include/execinfo.h
index 88f4ae7..84b637c 100644
--- a/libc/include/execinfo.h
+++ b/libc/include/execinfo.h
@@ -47,6 +47,8 @@
  *
  * Available since API level 33.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(33)
 int backtrace(void* _Nonnull * _Nonnull buffer, int size) __INTRODUCED_IN(33);
 
 /**
@@ -70,5 +72,7 @@
  * Available since API level 33.
  */
 void backtrace_symbols_fd(void* _Nonnull const* _Nonnull buffer, int size, int fd) __INTRODUCED_IN(33);
+#endif /* __BIONIC_AVAILABILITY_GUARD(33) */
+
 
 __END_DECLS
diff --git a/libc/include/fcntl.h b/libc/include/fcntl.h
index 1e9a285..2bd1fc6 100644
--- a/libc/include/fcntl.h
+++ b/libc/include/fcntl.h
@@ -227,7 +227,11 @@
  *
  * Returns 0 on success and returns -1 and sets `errno` on failure.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(26)
 int sync_file_range(int __fd, off64_t __offset, off64_t __length, unsigned int __flags) __INTRODUCED_IN(26);
+#endif /* __BIONIC_AVAILABILITY_GUARD(26) */
+
 
 #endif
 
diff --git a/libc/include/glob.h b/libc/include/glob.h
index 2c2b8d1..ccdf2e9 100644
--- a/libc/include/glob.h
+++ b/libc/include/glob.h
@@ -92,8 +92,12 @@
 
 __BEGIN_DECLS
 
+
+#if __BIONIC_AVAILABILITY_GUARD(28)
 int glob(const char* _Nonnull __pattern, int __flags, int (* _Nullable __error_callback)(const char* _Nonnull __failure_path, int __failure_errno), glob_t* _Nonnull __result_ptr) __INTRODUCED_IN(28);
 void globfree(glob_t* _Nonnull __result_ptr) __INTRODUCED_IN(28);
+#endif /* __BIONIC_AVAILABILITY_GUARD(28) */
+
 
 __END_DECLS
 
diff --git a/libc/include/grp.h b/libc/include/grp.h
index 2451db5..a48c046 100644
--- a/libc/include/grp.h
+++ b/libc/include/grp.h
@@ -51,12 +51,20 @@
 struct group* _Nullable getgrnam(const char* _Nonnull __name);
 
 /* Note: Android has thousands and thousands of ids to iterate through. */
+
+#if __BIONIC_AVAILABILITY_GUARD(26)
 struct group* _Nullable getgrent(void) __INTRODUCED_IN(26);
 
 void setgrent(void) __INTRODUCED_IN(26);
 void endgrent(void) __INTRODUCED_IN(26);
+#endif /* __BIONIC_AVAILABILITY_GUARD(26) */
+
+
+#if __BIONIC_AVAILABILITY_GUARD(24)
 int getgrgid_r(gid_t __gid, struct group* __BIONIC_COMPLICATED_NULLNESS __group, char* _Nonnull __buf, size_t __n, struct group* _Nullable * _Nonnull __result) __INTRODUCED_IN(24);
 int getgrnam_r(const char* _Nonnull __name, struct group* __BIONIC_COMPLICATED_NULLNESS __group, char* _Nonnull __buf, size_t __n, struct group* _Nullable *_Nonnull __result) __INTRODUCED_IN(24);
+#endif /* __BIONIC_AVAILABILITY_GUARD(24) */
+
 int getgrouplist(const char* _Nonnull __user, gid_t __group, gid_t* __BIONIC_COMPLICATED_NULLNESS __groups, int* _Nonnull __group_count);
 int initgroups(const char* _Nonnull __user, gid_t __group);
 
diff --git a/libc/include/iconv.h b/libc/include/iconv.h
index 9da46b4..35328ee 100644
--- a/libc/include/iconv.h
+++ b/libc/include/iconv.h
@@ -60,6 +60,8 @@
  *
  * Available since API level 28.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(28)
 iconv_t _Nonnull iconv_open(const char* _Nonnull __dst_encoding, const char* _Nonnull __src_encoding) __INTRODUCED_IN(28);
 
 /**
@@ -82,5 +84,7 @@
  * Available since API level 28.
  */
 int iconv_close(iconv_t _Nonnull __converter) __INTRODUCED_IN(28);
+#endif /* __BIONIC_AVAILABILITY_GUARD(28) */
+
 
 __END_DECLS
diff --git a/libc/include/ifaddrs.h b/libc/include/ifaddrs.h
index c4d0e10..87d2947 100644
--- a/libc/include/ifaddrs.h
+++ b/libc/include/ifaddrs.h
@@ -80,6 +80,8 @@
  *
  * Available since API level 24.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(24)
 int getifaddrs(struct ifaddrs* _Nullable * _Nonnull __list_ptr) __INTRODUCED_IN(24);
 
 /**
@@ -89,5 +91,7 @@
  * Available since API level 24.
  */
 void freeifaddrs(struct ifaddrs* _Nullable __ptr) __INTRODUCED_IN(24);
+#endif /* __BIONIC_AVAILABILITY_GUARD(24) */
+
 
 __END_DECLS
diff --git a/libc/include/langinfo.h b/libc/include/langinfo.h
index 2b43892..b9d695c 100644
--- a/libc/include/langinfo.h
+++ b/libc/include/langinfo.h
@@ -92,8 +92,12 @@
 #define NOEXPR 54
 #define CRNCYSTR 55
 
+
+#if __BIONIC_AVAILABILITY_GUARD(26)
 char* _Nonnull nl_langinfo(nl_item __item) __INTRODUCED_IN(26);
 char* _Nonnull nl_langinfo_l(nl_item __item, locale_t _Nonnull __l) __INTRODUCED_IN(26);
+#endif /* __BIONIC_AVAILABILITY_GUARD(26) */
+
 
 __END_DECLS
 
diff --git a/libc/include/malloc.h b/libc/include/malloc.h
index 2fa4b49..dc2ca2b 100644
--- a/libc/include/malloc.h
+++ b/libc/include/malloc.h
@@ -195,7 +195,11 @@
  *
  * Available since API level 23.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(23)
 int malloc_info(int __must_be_zero, FILE* _Nonnull __fp) __INTRODUCED_IN(23);
+#endif /* __BIONIC_AVAILABILITY_GUARD(23) */
+
 
 /**
  * mallopt() option to set the decay time. Valid values are -1, 0 and 1.
@@ -368,7 +372,11 @@
  *
  * Available since API level 26.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(26)
 int mallopt(int __option, int __value) __INTRODUCED_IN(26);
+#endif /* __BIONIC_AVAILABILITY_GUARD(26) */
+
 
 /**
  * [__malloc_hook(3)](https://man7.org/linux/man-pages/man3/__malloc_hook.3.html)
@@ -379,6 +387,8 @@
  *
  * See also: [extra documentation](https://android.googlesource.com/platform/bionic/+/main/libc/malloc_hooks/README.md)
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(28)
 extern void* _Nonnull (*volatile _Nonnull __malloc_hook)(size_t __byte_count, const void* _Nonnull __caller) __INTRODUCED_IN(28);
 
 /**
@@ -413,5 +423,7 @@
  * See also: [extra documentation](https://android.googlesource.com/platform/bionic/+/main/libc/malloc_hooks/README.md)
  */
 extern void* _Nonnull (*volatile _Nonnull __memalign_hook)(size_t __alignment, size_t __byte_count, const void* _Nonnull __caller) __INTRODUCED_IN(28);
+#endif /* __BIONIC_AVAILABILITY_GUARD(28) */
+
 
 __END_DECLS
diff --git a/libc/include/math.h b/libc/include/math.h
index 343ab98..59161bf 100644
--- a/libc/include/math.h
+++ b/libc/include/math.h
@@ -350,7 +350,11 @@
 double gamma_r(double __x, int* _Nonnull __sign);
 double lgamma_r(double __x, int* _Nonnull __sign);
 double significand(double __x);
+
+#if __BIONIC_AVAILABILITY_GUARD(23)
 long double lgammal_r(long double __x, int* _Nonnull __sign) __INTRODUCED_IN(23);
+#endif /* __BIONIC_AVAILABILITY_GUARD(23) */
+
 long double significandl(long double __x);
 float dremf(float __x, float __y);
 int finitef(float __x) __attribute_const__;
diff --git a/libc/include/mntent.h b/libc/include/mntent.h
index b4d1233..4c03602 100644
--- a/libc/include/mntent.h
+++ b/libc/include/mntent.h
@@ -62,7 +62,11 @@
 struct mntent* _Nullable getmntent(FILE* _Nonnull __fp);
 struct mntent* _Nullable getmntent_r(FILE* _Nonnull __fp, struct mntent* _Nonnull __entry, char* _Nonnull __buf, int __size);
 FILE* _Nullable setmntent(const char* _Nonnull __filename, const char* _Nonnull __type);
+
+#if __BIONIC_AVAILABILITY_GUARD(26)
 char* _Nullable hasmntopt(const struct mntent* _Nonnull __entry, const char* _Nonnull __option) __INTRODUCED_IN(26);
+#endif /* __BIONIC_AVAILABILITY_GUARD(26) */
+
 
 __END_DECLS
 
diff --git a/libc/include/net/if.h b/libc/include/net/if.h
index 4bbdb21..50bc74c 100644
--- a/libc/include/net/if.h
+++ b/libc/include/net/if.h
@@ -47,8 +47,12 @@
 
 char* _Nullable if_indextoname(unsigned __index, char* _Nonnull __buf);
 unsigned if_nametoindex(const char* _Nonnull __name);
+
+#if __BIONIC_AVAILABILITY_GUARD(24)
 struct if_nameindex* _Nullable if_nameindex(void) __INTRODUCED_IN(24);
 void if_freenameindex(struct if_nameindex* _Nullable __ptr) __INTRODUCED_IN(24);
+#endif /* __BIONIC_AVAILABILITY_GUARD(24) */
+
 
 __END_DECLS
 
diff --git a/libc/include/netdb.h b/libc/include/netdb.h
index 88214d5..04aaf5c 100644
--- a/libc/include/netdb.h
+++ b/libc/include/netdb.h
@@ -212,28 +212,52 @@
 void herror(const char* _Nonnull __s);
 const char* _Nonnull hstrerror(int __error);
 struct hostent* _Nullable gethostbyaddr(const void* _Nonnull __addr, socklen_t __length, int __type);
+
+#if __BIONIC_AVAILABILITY_GUARD(23)
 int gethostbyaddr_r(const void* _Nonnull __addr, socklen_t __length, int __type, struct hostent* _Nonnull __ret, char* _Nonnull __buf, size_t __buf_size, struct hostent* _Nullable * _Nonnull __result, int* _Nonnull __h_errno_ptr) __INTRODUCED_IN(23);
+#endif /* __BIONIC_AVAILABILITY_GUARD(23) */
+
 struct hostent* _Nullable gethostbyname(const char* _Nonnull __name);
 int gethostbyname_r(const char* _Nonnull __name, struct hostent* _Nonnull __ret, char* _Nonnull __buf, size_t __buf_size, struct hostent* _Nullable * _Nonnull __result, int* _Nonnull __h_errno_ptr);
 struct hostent* _Nullable gethostbyname2(const char* _Nonnull __name, int __af);
+
+#if __BIONIC_AVAILABILITY_GUARD(23)
 int gethostbyname2_r(const char* _Nonnull __name, int __af, struct hostent* _Nonnull __ret, char* _Nonnull __buf, size_t __buf_size, struct hostent* _Nullable * _Nonnull __result, int* _Nonnull __h_errno_ptr) __INTRODUCED_IN(23);
+#endif /* __BIONIC_AVAILABILITY_GUARD(23) */
+
+
+#if __BIONIC_AVAILABILITY_GUARD(28)
 void endhostent(void) __INTRODUCED_IN(28);
+#endif /* __BIONIC_AVAILABILITY_GUARD(28) */
+
 struct hostent* _Nullable gethostent(void);
+
+#if __BIONIC_AVAILABILITY_GUARD(28)
 void sethostent(int __stay_open) __INTRODUCED_IN(28);
 
 /* These functions are obsolete. None of these functions return anything but nullptr. */
 void endnetent(void) __INTRODUCED_IN(28);
+#endif /* __BIONIC_AVAILABILITY_GUARD(28) */
+
 struct netent* _Nullable getnetbyaddr(uint32_t __net, int __type);
 struct netent* _Nullable getnetbyname(const char* _Nonnull __name);
+
+#if __BIONIC_AVAILABILITY_GUARD(28)
 struct netent* _Nullable getnetent(void) __INTRODUCED_IN(28);
 void setnetent(int __stay_open) __INTRODUCED_IN(28);
 
 /* None of these functions return anything but nullptr. */
 void endprotoent(void) __INTRODUCED_IN(28);
+#endif /* __BIONIC_AVAILABILITY_GUARD(28) */
+
 struct protoent* _Nullable getprotobyname(const char* _Nonnull __name);
 struct protoent* _Nullable getprotobynumber(int __proto);
+
+#if __BIONIC_AVAILABILITY_GUARD(28)
 struct protoent* _Nullable getprotoent(void) __INTRODUCED_IN(28);
 void setprotoent(int __stay_open) __INTRODUCED_IN(28);
+#endif /* __BIONIC_AVAILABILITY_GUARD(28) */
+
 
 /* These functions return entries from a built-in database. */
 void endservent(void);
diff --git a/libc/include/nl_types.h b/libc/include/nl_types.h
index 6c9935d..172d80d 100644
--- a/libc/include/nl_types.h
+++ b/libc/include/nl_types.h
@@ -62,6 +62,8 @@
  *
  * Available since API level 28.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(26)
 nl_catd _Nonnull catopen(const char* _Nonnull __name, int __flag) __INTRODUCED_IN(26);
 
 /**
@@ -80,5 +82,7 @@
  * On Android, this always returns -1 with `errno` set to `EBADF`.
  */
 int catclose(nl_catd _Nonnull __catalog) __INTRODUCED_IN(26);
+#endif /* __BIONIC_AVAILABILITY_GUARD(26) */
+
 
 __END_DECLS
diff --git a/libc/include/poll.h b/libc/include/poll.h
index 0dda3da..e57f812 100644
--- a/libc/include/poll.h
+++ b/libc/include/poll.h
@@ -64,7 +64,11 @@
 /**
  * Like ppoll() but allows setting a signal mask with RT signals even from a 32-bit process.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(28)
 int ppoll64(struct pollfd* _Nullable  __fds, nfds_t __count, const struct timespec* _Nullable __timeout, const sigset64_t* _Nullable __mask) __INTRODUCED_IN(28);
+#endif /* __BIONIC_AVAILABILITY_GUARD(28) */
+
 
 #if defined(__BIONIC_INCLUDE_FORTIFY_HEADERS)
 #define _POLL_H_
diff --git a/libc/include/pthread.h b/libc/include/pthread.h
index 2fa10bb..8b78a74 100644
--- a/libc/include/pthread.h
+++ b/libc/include/pthread.h
@@ -99,7 +99,11 @@
 int pthread_attr_destroy(pthread_attr_t* _Nonnull __attr);
 int pthread_attr_getdetachstate(const pthread_attr_t* _Nonnull __attr, int* _Nonnull __state);
 int pthread_attr_getguardsize(const pthread_attr_t* _Nonnull __attr, size_t* _Nonnull __size);
+
+#if __BIONIC_AVAILABILITY_GUARD(28)
 int pthread_attr_getinheritsched(const pthread_attr_t* _Nonnull __attr, int* _Nonnull __flag) __INTRODUCED_IN(28);
+#endif /* __BIONIC_AVAILABILITY_GUARD(28) */
+
 int pthread_attr_getschedparam(const pthread_attr_t* _Nonnull __attr, struct sched_param* _Nonnull __param);
 int pthread_attr_getschedpolicy(const pthread_attr_t* _Nonnull __attr, int* _Nonnull __policy);
 int pthread_attr_getscope(const pthread_attr_t* _Nonnull __attr, int* _Nonnull __scope);
@@ -108,7 +112,11 @@
 int pthread_attr_init(pthread_attr_t* _Nonnull __attr);
 int pthread_attr_setdetachstate(pthread_attr_t* _Nonnull __attr, int __state);
 int pthread_attr_setguardsize(pthread_attr_t* _Nonnull __attr, size_t __size);
+
+#if __BIONIC_AVAILABILITY_GUARD(28)
 int pthread_attr_setinheritsched(pthread_attr_t* _Nonnull __attr, int __flag) __INTRODUCED_IN(28);
+#endif /* __BIONIC_AVAILABILITY_GUARD(28) */
+
 int pthread_attr_setschedparam(pthread_attr_t* _Nonnull __attr, const struct sched_param* _Nonnull __param);
 int pthread_attr_setschedpolicy(pthread_attr_t* _Nonnull __attr, int __policy);
 int pthread_attr_setscope(pthread_attr_t* _Nonnull __attr, int __scope);
@@ -123,8 +131,12 @@
 int pthread_condattr_setpshared(pthread_condattr_t* _Nonnull __attr, int __shared);
 
 int pthread_cond_broadcast(pthread_cond_t* _Nonnull __cond);
+
+#if __BIONIC_AVAILABILITY_GUARD(30)
 int pthread_cond_clockwait(pthread_cond_t* _Nonnull __cond, pthread_mutex_t* _Nonnull __mutex, clockid_t __clock,
                            const struct timespec* _Nullable __timeout) __INTRODUCED_IN(30);
+#endif /* __BIONIC_AVAILABILITY_GUARD(30) */
+
 int pthread_cond_destroy(pthread_cond_t* _Nonnull __cond);
 int pthread_cond_init(pthread_cond_t* _Nonnull __cond, const pthread_condattr_t* _Nullable __attr);
 int pthread_cond_signal(pthread_cond_t* _Nonnull __cond);
@@ -139,8 +151,12 @@
  * Note that pthread_cond_clockwait() allows specifying an arbitrary clock and has superseded this
  * function.
  */
+
+#if (!defined(__LP64__)) || (defined(__LP64__) && __ANDROID_API__ >= 28)
 int pthread_cond_timedwait_monotonic_np(pthread_cond_t* _Nonnull __cond, pthread_mutex_t* _Nonnull __mutex,
                                         const struct timespec* _Nullable __timeout) __INTRODUCED_IN_64(28);
+#endif /* (!defined(__LP64__)) || (defined(__LP64__) && __ANDROID_API__ >= 28) */
+
 int pthread_cond_wait(pthread_cond_t* _Nonnull __cond, pthread_mutex_t* _Nonnull __mutex);
 
 int pthread_create(pthread_t* _Nonnull __pthread_ptr, pthread_attr_t const* _Nullable __attr, void* _Nullable (* _Nonnull __start_routine)(void* _Nullable), void* _Nullable);
@@ -188,14 +204,26 @@
 int pthread_mutexattr_destroy(pthread_mutexattr_t* _Nonnull __attr);
 int pthread_mutexattr_getpshared(const pthread_mutexattr_t* _Nonnull __attr, int* _Nonnull __shared);
 int pthread_mutexattr_gettype(const pthread_mutexattr_t* _Nonnull __attr, int* _Nonnull __type);
+
+#if __BIONIC_AVAILABILITY_GUARD(28)
 int pthread_mutexattr_getprotocol(const pthread_mutexattr_t* _Nonnull __attr, int* _Nonnull __protocol) __INTRODUCED_IN(28);
+#endif /* __BIONIC_AVAILABILITY_GUARD(28) */
+
 int pthread_mutexattr_init(pthread_mutexattr_t* _Nonnull __attr);
 int pthread_mutexattr_setpshared(pthread_mutexattr_t* _Nonnull __attr, int __shared);
 int pthread_mutexattr_settype(pthread_mutexattr_t* _Nonnull __attr, int __type);
-int pthread_mutexattr_setprotocol(pthread_mutexattr_t* _Nonnull __attr, int __protocol) __INTRODUCED_IN(28);
 
+#if __BIONIC_AVAILABILITY_GUARD(28)
+int pthread_mutexattr_setprotocol(pthread_mutexattr_t* _Nonnull __attr, int __protocol) __INTRODUCED_IN(28);
+#endif /* __BIONIC_AVAILABILITY_GUARD(28) */
+
+
+
+#if __BIONIC_AVAILABILITY_GUARD(30)
 int pthread_mutex_clocklock(pthread_mutex_t* _Nonnull __mutex, clockid_t __clock,
                             const struct timespec* _Nullable __abstime) __INTRODUCED_IN(30);
+#endif /* __BIONIC_AVAILABILITY_GUARD(30) */
+
 int pthread_mutex_destroy(pthread_mutex_t* _Nonnull __mutex);
 int pthread_mutex_init(pthread_mutex_t* _Nonnull __mutex, const pthread_mutexattr_t* _Nullable __attr);
 int pthread_mutex_lock(pthread_mutex_t* _Nonnull __mutex);
@@ -210,8 +238,12 @@
  * Note that pthread_mutex_clocklock() allows specifying an arbitrary clock and has superseded this
  * function.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(28)
 int pthread_mutex_timedlock_monotonic_np(pthread_mutex_t* _Nonnull __mutex, const struct timespec* _Nullable __timeout)
     __INTRODUCED_IN(28);
+#endif /* __BIONIC_AVAILABILITY_GUARD(28) */
+
 int pthread_mutex_trylock(pthread_mutex_t* _Nonnull __mutex);
 int pthread_mutex_unlock(pthread_mutex_t* _Nonnull __mutex);
 
@@ -221,30 +253,48 @@
 int pthread_rwlockattr_destroy(pthread_rwlockattr_t* _Nonnull __attr);
 int pthread_rwlockattr_getpshared(const pthread_rwlockattr_t* _Nonnull __attr, int* _Nonnull __shared);
 int pthread_rwlockattr_setpshared(pthread_rwlockattr_t* _Nonnull __attr, int __shared);
+
+#if __BIONIC_AVAILABILITY_GUARD(23)
 int pthread_rwlockattr_getkind_np(const pthread_rwlockattr_t* _Nonnull __attr, int* _Nonnull __kind)
   __INTRODUCED_IN(23);
 int pthread_rwlockattr_setkind_np(pthread_rwlockattr_t* _Nonnull __attr, int __kind) __INTRODUCED_IN(23);
+#endif /* __BIONIC_AVAILABILITY_GUARD(23) */
 
+
+
+#if __BIONIC_AVAILABILITY_GUARD(30)
 int pthread_rwlock_clockrdlock(pthread_rwlock_t* _Nonnull __rwlock, clockid_t __clock,
                                const struct timespec* _Nullable __timeout) __INTRODUCED_IN(30);
 int pthread_rwlock_clockwrlock(pthread_rwlock_t* _Nonnull __rwlock, clockid_t __clock,
                                const struct timespec* _Nullable __timeout) __INTRODUCED_IN(30);
+#endif /* __BIONIC_AVAILABILITY_GUARD(30) */
+
 int pthread_rwlock_destroy(pthread_rwlock_t* _Nonnull __rwlock);
 int pthread_rwlock_init(pthread_rwlock_t* _Nonnull __rwlock, const pthread_rwlockattr_t* _Nullable __attr);
 int pthread_rwlock_rdlock(pthread_rwlock_t* _Nonnull __rwlock);
 int pthread_rwlock_timedrdlock(pthread_rwlock_t* _Nonnull __rwlock, const struct timespec* _Nullable __timeout);
 /* See the comment on pthread_mutex_timedlock_monotonic_np for usage of this function. */
+
+#if __BIONIC_AVAILABILITY_GUARD(28)
 int pthread_rwlock_timedrdlock_monotonic_np(pthread_rwlock_t* _Nonnull __rwlock,
                                             const struct timespec* _Nullable __timeout) __INTRODUCED_IN(28);
+#endif /* __BIONIC_AVAILABILITY_GUARD(28) */
+
 int pthread_rwlock_timedwrlock(pthread_rwlock_t* _Nonnull __rwlock, const struct timespec* _Nullable __timeout);
 /* See the comment on pthread_mutex_timedlock_monotonic_np for usage of this function. */
+
+#if __BIONIC_AVAILABILITY_GUARD(28)
 int pthread_rwlock_timedwrlock_monotonic_np(pthread_rwlock_t* _Nonnull __rwlock,
                                             const struct timespec* _Nullable __timeout) __INTRODUCED_IN(28);
+#endif /* __BIONIC_AVAILABILITY_GUARD(28) */
+
 int pthread_rwlock_tryrdlock(pthread_rwlock_t* _Nonnull __rwlock);
 int pthread_rwlock_trywrlock(pthread_rwlock_t* _Nonnull __rwlock);
 int pthread_rwlock_unlock(pthread_rwlock_t* _Nonnull __rwlock);
 int pthread_rwlock_wrlock(pthread_rwlock_t* _Nonnull __rwlock);
 
+
+#if __BIONIC_AVAILABILITY_GUARD(24)
 int pthread_barrierattr_init(pthread_barrierattr_t* _Nonnull __attr) __INTRODUCED_IN(24);
 int pthread_barrierattr_destroy(pthread_barrierattr_t* _Nonnull __attr) __INTRODUCED_IN(24);
 int pthread_barrierattr_getpshared(const pthread_barrierattr_t* _Nonnull __attr, int* _Nonnull __shared) __INTRODUCED_IN(24);
@@ -259,11 +309,17 @@
 int pthread_spin_lock(pthread_spinlock_t* _Nonnull __spinlock) __INTRODUCED_IN(24);
 int pthread_spin_trylock(pthread_spinlock_t* _Nonnull __spinlock) __INTRODUCED_IN(24);
 int pthread_spin_unlock(pthread_spinlock_t* _Nonnull __spinlock) __INTRODUCED_IN(24);
+#endif /* __BIONIC_AVAILABILITY_GUARD(24) */
+
 
 pthread_t pthread_self(void) __attribute_const__;
 
 #if defined(__USE_GNU)
+
+#if __BIONIC_AVAILABILITY_GUARD(26)
 int pthread_getname_np(pthread_t __pthread, char* _Nonnull __buf, size_t __n) __INTRODUCED_IN(26);
+#endif /* __BIONIC_AVAILABILITY_GUARD(26) */
+
 #endif
 /* TODO: this should be __USE_GNU too. */
 int pthread_setname_np(pthread_t __pthread, const char* _Nonnull __name);
@@ -302,7 +358,11 @@
  *
  * Available since API level 28.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(28)
 int pthread_setschedprio(pthread_t __pthread, int __priority) __INTRODUCED_IN(28);
+#endif /* __BIONIC_AVAILABILITY_GUARD(28) */
+
 
 int pthread_setspecific(pthread_key_t __key, const void* _Nullable __value);
 
diff --git a/libc/include/pty.h b/libc/include/pty.h
index 1cfb772..92d7fbb 100644
--- a/libc/include/pty.h
+++ b/libc/include/pty.h
@@ -49,6 +49,8 @@
  *
  * Available since API level 23.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(23)
 int openpty(int* _Nonnull __pty_fd, int* _Nonnull __tty_fd, char* _Nullable __tty_name, const struct termios* _Nullable __termios_ptr, const struct winsize* _Nullable __winsize_ptr) __INTRODUCED_IN(23);
 
 /**
@@ -61,5 +63,7 @@
  * Available since API level 23.
  */
 int forkpty(int* _Nonnull __parent_pty_fd, char* _Nullable __child_tty_name, const struct termios* _Nullable __termios_ptr, const struct winsize* _Nullable __winsize_ptr) __INTRODUCED_IN(23);
+#endif /* __BIONIC_AVAILABILITY_GUARD(23) */
+
 
 __END_DECLS
diff --git a/libc/include/pwd.h b/libc/include/pwd.h
index 2b17fbf..09592bc 100644
--- a/libc/include/pwd.h
+++ b/libc/include/pwd.h
@@ -84,10 +84,14 @@
 struct passwd* _Nullable getpwuid(uid_t __uid);
 
 /* Note: Android has thousands and thousands of ids to iterate through */
+
+#if __BIONIC_AVAILABILITY_GUARD(26)
 struct passwd* _Nullable getpwent(void) __INTRODUCED_IN(26);
 
 void setpwent(void) __INTRODUCED_IN(26);
 void endpwent(void) __INTRODUCED_IN(26);
+#endif /* __BIONIC_AVAILABILITY_GUARD(26) */
+
 
 int getpwnam_r(const char* _Nonnull __name, struct passwd* _Nonnull __pwd, char* _Nonnull __buf, size_t __n, struct passwd* _Nullable * _Nonnull __result);
 int getpwuid_r(uid_t __uid, struct passwd* _Nonnull __pwd, char* _Nonnull __buf, size_t __n, struct passwd* _Nullable * _Nonnull __result);
diff --git a/libc/include/resolv.h b/libc/include/resolv.h
index 4367359..c49cefc 100644
--- a/libc/include/resolv.h
+++ b/libc/include/resolv.h
@@ -61,7 +61,11 @@
 int res_search(const char* _Nonnull __name, int __class, int __type, u_char* _Nonnull __answer, int __answer_size);
 
 #define res_randomid __res_randomid
+
+#if __BIONIC_AVAILABILITY_GUARD(29)
 u_int __res_randomid(void) __INTRODUCED_IN(29);
+#endif /* __BIONIC_AVAILABILITY_GUARD(29) */
+
 
 __END_DECLS
 
diff --git a/libc/include/search.h b/libc/include/search.h
index 85e31ee..2f43d91 100644
--- a/libc/include/search.h
+++ b/libc/include/search.h
@@ -85,6 +85,8 @@
  *
  * Available since API level 28.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(28)
 int hcreate(size_t __n) __INTRODUCED_IN(28);
 
 /**
@@ -109,6 +111,8 @@
  * Available since API level 28.
  */
 ENTRY* _Nullable hsearch(ENTRY __entry, ACTION __action) __INTRODUCED_IN(28);
+#endif /* __BIONIC_AVAILABILITY_GUARD(28) */
+
 
 #if defined(__USE_BSD) || defined(__USE_GNU)
 
@@ -120,6 +124,8 @@
  *
  * Available since API level 28.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(28)
 int hcreate_r(size_t __n, struct hsearch_data* _Nonnull __table) __INTRODUCED_IN(28);
 
 /**
@@ -140,6 +146,8 @@
  * Available since API level 28.
  */
 int hsearch_r(ENTRY __entry, ACTION __action, ENTRY* _Nullable * _Nonnull __result, struct hsearch_data* _Nonnull __table) __INTRODUCED_IN(28);
+#endif /* __BIONIC_AVAILABILITY_GUARD(28) */
+
 
 #endif
 
diff --git a/libc/include/semaphore.h b/libc/include/semaphore.h
index 6ad9ea3..9c4702d 100644
--- a/libc/include/semaphore.h
+++ b/libc/include/semaphore.h
@@ -45,7 +45,11 @@
 
 #define SEM_FAILED __BIONIC_CAST(reinterpret_cast, sem_t*, 0)
 
+
+#if __BIONIC_AVAILABILITY_GUARD(30)
 int sem_clockwait(sem_t* _Nonnull __sem, clockid_t __clock, const struct timespec* _Nonnull __ts) __INTRODUCED_IN(30);
+#endif /* __BIONIC_AVAILABILITY_GUARD(30) */
+
 int sem_destroy(sem_t* _Nonnull __sem);
 int sem_getvalue(sem_t* _Nonnull __sem, int* _Nonnull __value);
 int sem_init(sem_t* _Nonnull __sem, int __shared, unsigned int __value);
@@ -59,7 +63,11 @@
  * Note that sem_clockwait() allows specifying an arbitrary clock and has superseded this
  * function.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(28)
 int sem_timedwait_monotonic_np(sem_t* _Nonnull __sem, const struct timespec* _Nonnull __ts) __INTRODUCED_IN(28);
+#endif /* __BIONIC_AVAILABILITY_GUARD(28) */
+
 int sem_trywait(sem_t* _Nonnull __sem);
 int sem_wait(sem_t* _Nonnull __sem);
 
diff --git a/libc/include/signal.h b/libc/include/signal.h
index 893fa9d..38dcbde 100644
--- a/libc/include/signal.h
+++ b/libc/include/signal.h
@@ -60,31 +60,73 @@
 #define si_timerid si_tid /* glibc compatibility. */
 
 int sigaction(int __signal, const struct sigaction* _Nullable __new_action, struct sigaction* _Nullable __old_action);
+
+#if __BIONIC_AVAILABILITY_GUARD(28)
 int sigaction64(int __signal, const struct sigaction64* _Nullable __new_action, struct sigaction64* _Nullable __old_action) __INTRODUCED_IN(28);
+#endif /* __BIONIC_AVAILABILITY_GUARD(28) */
+
 
 int siginterrupt(int __signal, int __flag);
 
 sighandler_t _Nonnull signal(int __signal, sighandler_t _Nullable __handler);
 int sigaddset(sigset_t* _Nonnull __set, int __signal);
+
+#if __BIONIC_AVAILABILITY_GUARD(28)
 int sigaddset64(sigset64_t* _Nonnull __set, int __signal) __INTRODUCED_IN(28);
+#endif /* __BIONIC_AVAILABILITY_GUARD(28) */
+
 int sigdelset(sigset_t* _Nonnull __set, int __signal);
+
+#if __BIONIC_AVAILABILITY_GUARD(28)
 int sigdelset64(sigset64_t* _Nonnull __set, int __signal) __INTRODUCED_IN(28);
+#endif /* __BIONIC_AVAILABILITY_GUARD(28) */
+
 int sigemptyset(sigset_t* _Nonnull __set);
+
+#if __BIONIC_AVAILABILITY_GUARD(28)
 int sigemptyset64(sigset64_t* _Nonnull __set) __INTRODUCED_IN(28);
+#endif /* __BIONIC_AVAILABILITY_GUARD(28) */
+
 int sigfillset(sigset_t* _Nonnull __set);
+
+#if __BIONIC_AVAILABILITY_GUARD(28)
 int sigfillset64(sigset64_t* _Nonnull __set) __INTRODUCED_IN(28);
+#endif /* __BIONIC_AVAILABILITY_GUARD(28) */
+
 int sigismember(const sigset_t* _Nonnull __set, int __signal);
+
+#if __BIONIC_AVAILABILITY_GUARD(28)
 int sigismember64(const sigset64_t* _Nonnull __set, int __signal) __INTRODUCED_IN(28);
+#endif /* __BIONIC_AVAILABILITY_GUARD(28) */
+
 
 int sigpending(sigset_t* _Nonnull __set);
-int sigpending64(sigset64_t* _Nonnull __set) __INTRODUCED_IN(28);
-int sigprocmask(int __how, const sigset_t* _Nullable __new_set, sigset_t* _Nullable __old_set);
-int sigprocmask64(int __how, const sigset64_t* _Nullable __new_set, sigset64_t* _Nullable __old_set) __INTRODUCED_IN(28);
-int sigsuspend(const sigset_t* _Nonnull __mask);
-int sigsuspend64(const sigset64_t* _Nonnull __mask) __INTRODUCED_IN(28);
-int sigwait(const sigset_t* _Nonnull __set, int* _Nonnull __signal);
-int sigwait64(const sigset64_t* _Nonnull __set, int* _Nonnull __signal) __INTRODUCED_IN(28);
 
+#if __BIONIC_AVAILABILITY_GUARD(28)
+int sigpending64(sigset64_t* _Nonnull __set) __INTRODUCED_IN(28);
+#endif /* __BIONIC_AVAILABILITY_GUARD(28) */
+
+int sigprocmask(int __how, const sigset_t* _Nullable __new_set, sigset_t* _Nullable __old_set);
+
+#if __BIONIC_AVAILABILITY_GUARD(28)
+int sigprocmask64(int __how, const sigset64_t* _Nullable __new_set, sigset64_t* _Nullable __old_set) __INTRODUCED_IN(28);
+#endif /* __BIONIC_AVAILABILITY_GUARD(28) */
+
+int sigsuspend(const sigset_t* _Nonnull __mask);
+
+#if __BIONIC_AVAILABILITY_GUARD(28)
+int sigsuspend64(const sigset64_t* _Nonnull __mask) __INTRODUCED_IN(28);
+#endif /* __BIONIC_AVAILABILITY_GUARD(28) */
+
+int sigwait(const sigset_t* _Nonnull __set, int* _Nonnull __signal);
+
+#if __BIONIC_AVAILABILITY_GUARD(28)
+int sigwait64(const sigset64_t* _Nonnull __set, int* _Nonnull __signal) __INTRODUCED_IN(28);
+#endif /* __BIONIC_AVAILABILITY_GUARD(28) */
+
+
+
+#if __BIONIC_AVAILABILITY_GUARD(26)
 int sighold(int __signal)
   __attribute__((__deprecated__("use sigprocmask() or pthread_sigmask() instead")))
   __INTRODUCED_IN(26);
@@ -97,6 +139,8 @@
   __INTRODUCED_IN(26);
 sighandler_t _Nonnull sigset(int __signal, sighandler_t _Nullable __handler)
   __attribute__((__deprecated__("use sigaction() instead"))) __INTRODUCED_IN(26);
+#endif /* __BIONIC_AVAILABILITY_GUARD(26) */
+
 
 int raise(int __signal);
 int kill(pid_t __pid, int __signal);
@@ -110,17 +154,41 @@
 
 int pthread_kill(pthread_t __pthread, int __signal);
 #if defined(__USE_GNU)
+
+#if __BIONIC_AVAILABILITY_GUARD(29)
 int pthread_sigqueue(pthread_t __pthread, int __signal, const union sigval __value) __INTRODUCED_IN(29);
+#endif /* __BIONIC_AVAILABILITY_GUARD(29) */
+
 #endif
 
 int pthread_sigmask(int __how, const sigset_t* _Nullable __new_set, sigset_t* _Nullable __old_set);
-int pthread_sigmask64(int __how, const sigset64_t* _Nullable __new_set, sigset64_t* _Nullable __old_set) __INTRODUCED_IN(28);
 
+#if __BIONIC_AVAILABILITY_GUARD(28)
+int pthread_sigmask64(int __how, const sigset64_t* _Nullable __new_set, sigset64_t* _Nullable __old_set) __INTRODUCED_IN(28);
+#endif /* __BIONIC_AVAILABILITY_GUARD(28) */
+
+
+
+#if __BIONIC_AVAILABILITY_GUARD(23)
 int sigqueue(pid_t __pid, int __signal, const union sigval __value) __INTRODUCED_IN(23);
 int sigtimedwait(const sigset_t* _Nonnull __set, siginfo_t* _Nullable __info, const struct timespec* _Nullable __timeout) __INTRODUCED_IN(23);
+#endif /* __BIONIC_AVAILABILITY_GUARD(23) */
+
+
+#if __BIONIC_AVAILABILITY_GUARD(28)
 int sigtimedwait64(const sigset64_t* _Nonnull __set, siginfo_t* _Nullable __info, const struct timespec* _Nullable __timeout) __INTRODUCED_IN(28);
+#endif /* __BIONIC_AVAILABILITY_GUARD(28) */
+
+
+#if __BIONIC_AVAILABILITY_GUARD(23)
 int sigwaitinfo(const sigset_t* _Nonnull __set, siginfo_t* _Nullable __info) __INTRODUCED_IN(23);
+#endif /* __BIONIC_AVAILABILITY_GUARD(23) */
+
+
+#if __BIONIC_AVAILABILITY_GUARD(28)
 int sigwaitinfo64(const sigset64_t* _Nonnull __set, siginfo_t* _Nullable __info) __INTRODUCED_IN(28);
+#endif /* __BIONIC_AVAILABILITY_GUARD(28) */
+
 
 /**
  * Buffer size suitable for any call to sig2str().
@@ -137,6 +205,8 @@
  *
  * Available since API level 36.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(36)
 int sig2str(int __signal, char* _Nonnull __buf) __INTRODUCED_IN(36);
 
 /**
@@ -149,6 +219,8 @@
  * Available since API level 36.
  */
 int str2sig(const char* _Nonnull __name, int* _Nonnull __signal) __INTRODUCED_IN(36);
+#endif /* __BIONIC_AVAILABILITY_GUARD(36) */
+
 
 __END_DECLS
 
diff --git a/libc/include/spawn.h b/libc/include/spawn.h
index f366239..b105754 100644
--- a/libc/include/spawn.h
+++ b/libc/include/spawn.h
@@ -55,6 +55,8 @@
 typedef struct __posix_spawnattr* posix_spawnattr_t;
 typedef struct __posix_spawn_file_actions* posix_spawn_file_actions_t;
 
+
+#if __BIONIC_AVAILABILITY_GUARD(28)
 int posix_spawn(pid_t* _Nullable __pid, const char* _Nonnull __path, const posix_spawn_file_actions_t _Nullable * _Nullable __actions, const posix_spawnattr_t _Nullable * _Nullable __attr, char* const _Nullable __argv[_Nullable], char* const _Nullable __env[_Nullable]) __INTRODUCED_IN(28);
 int posix_spawnp(pid_t* _Nullable __pid, const char* _Nonnull __file, const posix_spawn_file_actions_t _Nullable * _Nullable __actions, const posix_spawnattr_t _Nullable * _Nullable __attr, char* const _Nullable __argv[_Nullable], char* const _Nullable __env[_Nullable]) __INTRODUCED_IN(28);
 
@@ -89,9 +91,15 @@
 int posix_spawn_file_actions_addopen(posix_spawn_file_actions_t _Nonnull * _Nonnull __actions, int __fd, const char* _Nonnull __path, int __flags, mode_t __mode) __INTRODUCED_IN(28);
 int posix_spawn_file_actions_addclose(posix_spawn_file_actions_t _Nonnull * _Nonnull __actions, int __fd) __INTRODUCED_IN(28);
 int posix_spawn_file_actions_adddup2(posix_spawn_file_actions_t _Nonnull * _Nonnull __actions, int __fd, int __new_fd) __INTRODUCED_IN(28);
+#endif /* __BIONIC_AVAILABILITY_GUARD(28) */
 
+
+
+#if __BIONIC_AVAILABILITY_GUARD(34)
 int posix_spawn_file_actions_addchdir_np(posix_spawn_file_actions_t _Nonnull * _Nonnull __actions, const char* _Nonnull __path) __INTRODUCED_IN(34);
 int posix_spawn_file_actions_addfchdir_np(posix_spawn_file_actions_t _Nonnull * _Nonnull __actions, int __fd) __INTRODUCED_IN(34);
+#endif /* __BIONIC_AVAILABILITY_GUARD(34) */
+
 
 __END_DECLS
 
diff --git a/libc/include/stdio.h b/libc/include/stdio.h
index 4912c0a..2c2dc01 100644
--- a/libc/include/stdio.h
+++ b/libc/include/stdio.h
@@ -196,7 +196,11 @@
  *
  * Returns 0 on success, and returns -1 and sets `errno` on failure.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(30)
 int renameat2(int __old_dir_fd, const char* _Nonnull __old_path, int __new_dir_fd, const char* _Nonnull __new_path, unsigned __flags) __INTRODUCED_IN(30);
+#endif /* __BIONIC_AVAILABILITY_GUARD(30) */
+
 
 #endif
 
@@ -205,17 +209,25 @@
 
 /* See https://android.googlesource.com/platform/bionic/+/main/docs/32-bit-abi.md */
 #if defined(__USE_FILE_OFFSET64)
+
+#if __BIONIC_AVAILABILITY_GUARD(24)
 int fgetpos(FILE* _Nonnull __fp, fpos_t* _Nonnull __pos) __RENAME(fgetpos64) __INTRODUCED_IN(24);
 int fsetpos(FILE* _Nonnull __fp, const fpos_t* _Nonnull __pos) __RENAME(fsetpos64) __INTRODUCED_IN(24);
 int fseeko(FILE* _Nonnull __fp, off_t __offset, int __whence) __RENAME(fseeko64) __INTRODUCED_IN(24);
 __nodiscard off_t ftello(FILE* _Nonnull __fp) __RENAME(ftello64) __INTRODUCED_IN(24);
+#endif /* __BIONIC_AVAILABILITY_GUARD(24) */
+
 #  if defined(__USE_BSD)
 /* If __read_fn and __write_fn are both nullptr, it will cause EINVAL */
+
+#if __BIONIC_AVAILABILITY_GUARD(24)
 __nodiscard FILE* _Nullable funopen(const void* _Nullable __cookie,
               int (* __BIONIC_COMPLICATED_NULLNESS __read_fn)(void* _Nonnull, char* _Nonnull, int),
               int (* __BIONIC_COMPLICATED_NULLNESS __write_fn)(void* _Nonnull, const char* _Nonnull, int),
               fpos_t (* _Nullable __seek_fn)(void* _Nonnull, fpos_t, int),
               int (* _Nullable __close_fn)(void* _Nonnull)) __RENAME(funopen64) __INTRODUCED_IN(24);
+#endif /* __BIONIC_AVAILABILITY_GUARD(24) */
+
 #  endif
 #else
 int fgetpos(FILE* _Nonnull __fp, fpos_t* _Nonnull __pos);
@@ -231,25 +243,45 @@
               int (* _Nullable __close_fn)(void* _Nonnull));
 #  endif
 #endif
+
+#if __BIONIC_AVAILABILITY_GUARD(24)
 int fgetpos64(FILE* _Nonnull __fp, fpos64_t* _Nonnull __pos) __INTRODUCED_IN(24);
 int fsetpos64(FILE* _Nonnull __fp, const fpos64_t* _Nonnull __pos) __INTRODUCED_IN(24);
 int fseeko64(FILE* _Nonnull __fp, off64_t __offset, int __whence) __INTRODUCED_IN(24);
 __nodiscard off64_t ftello64(FILE* _Nonnull __fp) __INTRODUCED_IN(24);
+#endif /* __BIONIC_AVAILABILITY_GUARD(24) */
+
 #if defined(__USE_BSD)
 /* If __read_fn and __write_fn are both nullptr, it will cause EINVAL */
+
+#if __BIONIC_AVAILABILITY_GUARD(24)
 __nodiscard FILE* _Nullable funopen64(const void* _Nullable __cookie,
                 int (* __BIONIC_COMPLICATED_NULLNESS __read_fn)(void* _Nonnull, char* _Nonnull, int),
                 int (* __BIONIC_COMPLICATED_NULLNESS __write_fn)(void* _Nonnull, const char* _Nonnull, int),
                 fpos64_t (* _Nullable __seek_fn)(void* _Nonnull, fpos64_t, int),
                 int (* _Nullable __close_fn)(void* _Nonnull)) __INTRODUCED_IN(24);
+#endif /* __BIONIC_AVAILABILITY_GUARD(24) */
+
 #endif
 
 __nodiscard FILE* _Nullable fopen(const char* _Nonnull __path, const char* _Nonnull __mode);
+
+#if __BIONIC_AVAILABILITY_GUARD(24)
 __nodiscard FILE* _Nullable fopen64(const char* _Nonnull __path, const char* _Nonnull __mode) __INTRODUCED_IN(24);
+#endif /* __BIONIC_AVAILABILITY_GUARD(24) */
+
 FILE* _Nullable freopen(const char* _Nullable __path, const char* _Nonnull __mode, FILE* _Nonnull __fp);
+
+#if __BIONIC_AVAILABILITY_GUARD(24)
 FILE* _Nullable freopen64(const char* _Nullable __path, const char* _Nonnull __mode, FILE* _Nonnull __fp) __INTRODUCED_IN(24);
+#endif /* __BIONIC_AVAILABILITY_GUARD(24) */
+
 __nodiscard FILE* _Nullable tmpfile(void);
+
+#if __BIONIC_AVAILABILITY_GUARD(24)
 __nodiscard FILE* _Nullable tmpfile64(void) __INTRODUCED_IN(24);
+#endif /* __BIONIC_AVAILABILITY_GUARD(24) */
+
 
 int snprintf(char* __BIONIC_COMPLICATED_NULLNESS __buf, size_t __size, const char* _Nonnull __fmt, ...) __printflike(3, 4);
 int vfscanf(FILE* _Nonnull __fp, const char* _Nonnull __fmt, va_list __args) __scanflike(2, 0);
@@ -258,7 +290,11 @@
 int vsscanf(const char* _Nonnull __s, const char* _Nonnull __fmt, va_list __args) __scanflike(2, 0);
 
 #define L_ctermid 1024 /* size for ctermid() */
+
+#if __BIONIC_AVAILABILITY_GUARD(26)
 char* _Nonnull ctermid(char* _Nullable __buf) __INTRODUCED_IN(26);
+#endif /* __BIONIC_AVAILABILITY_GUARD(26) */
+
 
 __nodiscard FILE* _Nullable fdopen(int __fd, const char* _Nonnull __mode);
 __nodiscard int fileno(FILE* _Nonnull __fp);
@@ -272,13 +308,12 @@
 int putc_unlocked(int __ch, FILE* _Nonnull __fp);
 int putchar_unlocked(int __ch);
 
-// This causes issues with a polyfill in libconfuse
-// https://github.com/android/ndk/issues/2081
-#if __ANDROID_API__ >= 23
-__nodiscard FILE* _Nullable fmemopen(void* _Nullable __buf, size_t __size, const char* _Nonnull __mode) __INTRODUCED_IN(23);
-#endif
 
+#if __BIONIC_AVAILABILITY_GUARD(23)
+__nodiscard FILE* _Nullable fmemopen(void* _Nullable __buf, size_t __size, const char* _Nonnull __mode) __INTRODUCED_IN(23);
 __nodiscard FILE* _Nullable open_memstream(char* _Nonnull * _Nonnull __ptr, size_t* _Nonnull __size_ptr) __INTRODUCED_IN(23);
+#endif /* __BIONIC_AVAILABILITY_GUARD(23) */
+
 
 #if defined(__USE_BSD) || defined(__BIONIC__) /* Historically bionic exposed these. */
 int  asprintf(char* _Nullable * _Nonnull __s_ptr, const char* _Nonnull __fmt, ...) __printflike(2, 3);
@@ -287,25 +322,41 @@
 void setbuffer(FILE* _Nonnull __fp, char* _Nullable __buf, int __size);
 int setlinebuf(FILE* _Nonnull __fp);
 int vasprintf(char* _Nullable * _Nonnull __s_ptr, const char* _Nonnull __fmt, va_list __args) __printflike(2, 0);
+
+#if __BIONIC_AVAILABILITY_GUARD(23)
 void clearerr_unlocked(FILE* _Nonnull __fp) __INTRODUCED_IN(23);
 __nodiscard int feof_unlocked(FILE* _Nonnull __fp) __INTRODUCED_IN(23);
 __nodiscard int ferror_unlocked(FILE* _Nonnull __fp) __INTRODUCED_IN(23);
+#endif /* __BIONIC_AVAILABILITY_GUARD(23) */
+
+
+#if __BIONIC_AVAILABILITY_GUARD(24)
 __nodiscard int fileno_unlocked(FILE* _Nonnull __fp) __INTRODUCED_IN(24);
+#endif /* __BIONIC_AVAILABILITY_GUARD(24) */
+
 #define fropen(cookie, fn) funopen(cookie, fn, 0, 0, 0)
 #define fwopen(cookie, fn) funopen(cookie, 0, fn, 0, 0)
 #endif
 
 #if defined(__USE_BSD)
+
+#if __BIONIC_AVAILABILITY_GUARD(28)
 int fflush_unlocked(FILE* _Nullable __fp) __INTRODUCED_IN(28);
 __nodiscard int fgetc_unlocked(FILE* _Nonnull __fp) __INTRODUCED_IN(28);
 int fputc_unlocked(int __ch, FILE* _Nonnull __fp) __INTRODUCED_IN(28);
 size_t fread_unlocked(void* _Nonnull __buf, size_t __size, size_t __count, FILE* _Nonnull __fp) __INTRODUCED_IN(28);
 size_t fwrite_unlocked(const void* _Nonnull __buf, size_t __size, size_t __count, FILE* _Nonnull __fp) __INTRODUCED_IN(28);
+#endif /* __BIONIC_AVAILABILITY_GUARD(28) */
+
 #endif
 
 #if defined(__USE_GNU)
+
+#if __BIONIC_AVAILABILITY_GUARD(28)
 int fputs_unlocked(const char* _Nonnull __s, FILE* _Nonnull __fp) __INTRODUCED_IN(28);
 char* _Nullable fgets_unlocked(char* _Nonnull __buf, int __size, FILE* _Nonnull __fp) __INTRODUCED_IN(28);
+#endif /* __BIONIC_AVAILABILITY_GUARD(28) */
+
 #endif
 
 #if defined(__BIONIC_INCLUDE_FORTIFY_HEADERS)
diff --git a/libc/include/stdio_ext.h b/libc/include/stdio_ext.h
index d426a4a..9ff07da 100644
--- a/libc/include/stdio_ext.h
+++ b/libc/include/stdio_ext.h
@@ -44,6 +44,8 @@
  *
  * Available since API level 23.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(23)
 size_t __fbufsize(FILE* _Nonnull __fp) __INTRODUCED_IN(23);
 
 /**
@@ -53,6 +55,8 @@
  * Available since API level 23.
  */
 int __freadable(FILE* _Nonnull __fp) __INTRODUCED_IN(23);
+#endif /* __BIONIC_AVAILABILITY_GUARD(23) */
+
 
 /**
  * [__freading(3)](https://man7.org/linux/man-pages/man3/__freading.3.html) returns non-zero if
@@ -60,7 +64,11 @@
  *
  * Available since API level 28.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(28)
 int __freading(FILE* _Nonnull __fp) __INTRODUCED_IN(28);
+#endif /* __BIONIC_AVAILABILITY_GUARD(28) */
+
 
 /**
  * [__fwritable(3)](https://man7.org/linux/man-pages/man3/__fwritable.3.html) returns non-zero if
@@ -68,7 +76,11 @@
  *
  * Available since API level 23.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(23)
 int __fwritable(FILE* _Nonnull __fp) __INTRODUCED_IN(23);
+#endif /* __BIONIC_AVAILABILITY_GUARD(23) */
+
 
 /**
  * [__fwriting(3)](https://man7.org/linux/man-pages/man3/__fwriting.3.html) returns non-zero if
@@ -76,7 +88,11 @@
  *
  * Available since API level 28.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(28)
 int __fwriting(FILE* _Nonnull __fp) __INTRODUCED_IN(28);
+#endif /* __BIONIC_AVAILABILITY_GUARD(28) */
+
 
 /**
  * [__flbf(3)](https://man7.org/linux/man-pages/man3/__flbf.3.html) returns non-zero if
@@ -84,7 +100,11 @@
  *
  * Available since API level 23.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(23)
 int __flbf(FILE* _Nonnull __fp) __INTRODUCED_IN(23);
+#endif /* __BIONIC_AVAILABILITY_GUARD(23) */
+
 
 /**
  * [__fpurge(3)](https://man7.org/linux/man-pages/man3/__fpurge.3.html) discards the contents of
@@ -98,7 +118,11 @@
  *
  * Available since API level 23.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(23)
 size_t __fpending(FILE* _Nonnull __fp) __INTRODUCED_IN(23);
+#endif /* __BIONIC_AVAILABILITY_GUARD(23) */
+
 
 /**
  * __freadahead(3) returns the number of bytes in the input buffer.
@@ -106,7 +130,11 @@
  *
  * Available since API level 34.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(34)
 size_t __freadahead(FILE* _Nonnull __fp) __INTRODUCED_IN(34);
+#endif /* __BIONIC_AVAILABILITY_GUARD(34) */
+
 
 /**
  * [_flushlbf(3)](https://man7.org/linux/man-pages/man3/_flushlbf.3.html) flushes all
@@ -114,7 +142,11 @@
  *
  * Available since API level 23.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(23)
 void _flushlbf(void) __INTRODUCED_IN(23);
+#endif /* __BIONIC_AVAILABILITY_GUARD(23) */
+
 
 /**
  * `__fseterr` sets the
@@ -122,7 +154,11 @@
  *
  * Available since API level 28.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(28)
 void __fseterr(FILE* _Nonnull __fp) __INTRODUCED_IN(28);
+#endif /* __BIONIC_AVAILABILITY_GUARD(28) */
+
 
 /** __fsetlocking() constant to query locking type. */
 #define FSETLOCKING_QUERY 0
@@ -139,6 +175,10 @@
  *
  * Available since API level 23.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(23)
 int __fsetlocking(FILE* _Nonnull __fp, int __type) __INTRODUCED_IN(23);
+#endif /* __BIONIC_AVAILABILITY_GUARD(23) */
+
 
 __END_DECLS
diff --git a/libc/include/stdlib.h b/libc/include/stdlib.h
index 2c918d4..7081d7c 100644
--- a/libc/include/stdlib.h
+++ b/libc/include/stdlib.h
@@ -60,13 +60,21 @@
 char* _Nullable mkdtemp(char* _Nonnull __template);
 char* _Nullable mktemp(char* _Nonnull __template) __attribute__((__deprecated__("mktemp is unsafe, use mkstemp or tmpfile instead")));
 
+
+#if __BIONIC_AVAILABILITY_GUARD(23)
 int mkostemp64(char* _Nonnull __template, int __flags) __INTRODUCED_IN(23);
 int mkostemp(char* _Nonnull __template, int __flags) __INTRODUCED_IN(23);
 int mkostemps64(char* _Nonnull __template, int __suffix_length, int __flags) __INTRODUCED_IN(23);
 int mkostemps(char* _Nonnull __template, int __suffix_length, int __flags) __INTRODUCED_IN(23);
+#endif /* __BIONIC_AVAILABILITY_GUARD(23) */
+
 int mkstemp64(char* _Nonnull __template);
 int mkstemp(char* _Nonnull __template);
+
+#if __BIONIC_AVAILABILITY_GUARD(23)
 int mkstemps64(char* _Nonnull __template, int __flags) __INTRODUCED_IN(23);
+#endif /* __BIONIC_AVAILABILITY_GUARD(23) */
+
 int mkstemps(char* _Nonnull __template, int __flags);
 
 int posix_memalign(void* _Nullable * _Nullable __memptr, size_t __alignment, size_t __size);
@@ -80,7 +88,11 @@
  *
  * Available since API level 28.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(28)
 __nodiscard void* _Nullable aligned_alloc(size_t __alignment, size_t __size) __INTRODUCED_IN(28);
+#endif /* __BIONIC_AVAILABILITY_GUARD(28) */
+
 
 __nodiscard char* _Nullable realpath(const char* _Nonnull __path, char* _Nullable __resolved);
 
@@ -123,7 +135,11 @@
  *
  * Available since API level 36.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(36)
 void qsort_r(void* _Nullable __array, size_t __n, size_t __size, int (* _Nonnull __comparator)(const void* _Nullable __lhs, const void* _Nullable __rhs, void* _Nullable __context), void* _Nullable __context) __INTRODUCED_IN(36);
+#endif /* __BIONIC_AVAILABILITY_GUARD(36) */
+
 
 uint32_t arc4random(void);
 uint32_t arc4random_uniform(uint32_t __upper_bound);
@@ -136,7 +152,11 @@
 double drand48(void);
 double erand48(unsigned short __xsubi[_Nonnull 3]);
 long jrand48(unsigned short __xsubi[_Nonnull 3]);
+
+#if __BIONIC_AVAILABILITY_GUARD(23)
 void lcong48(unsigned short __param[_Nonnull 7]) __INTRODUCED_IN(23);
+#endif /* __BIONIC_AVAILABILITY_GUARD(23) */
+
 long lrand48(void);
 long mrand48(void);
 long nrand48(unsigned short __xsubi[_Nonnull 3]);
@@ -152,7 +172,11 @@
 int ptsname_r(int __fd, char* _Nonnull __buf, size_t __n);
 int unlockpt(int __fd);
 
+
+#if __BIONIC_AVAILABILITY_GUARD(26)
 int getsubopt(char* _Nonnull * _Nonnull __option, char* _Nonnull const* _Nonnull __tokens, char* _Nullable * _Nonnull __value_ptr) __INTRODUCED_IN(26);
+#endif /* __BIONIC_AVAILABILITY_GUARD(26) */
+
 
 typedef struct {
   int quot;
@@ -182,13 +206,21 @@
  *
  * Returns the number of samples written to `__averages` (at most 3), and returns -1 on failure.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(29)
 int getloadavg(double __averages[_Nonnull], int __n) __INTRODUCED_IN(29);
+#endif /* __BIONIC_AVAILABILITY_GUARD(29) */
+
 
 /* BSD compatibility. */
 const char* _Nullable getprogname(void);
 void setprogname(const char* _Nonnull __name);
 
+
+#if __BIONIC_AVAILABILITY_GUARD(26)
 int mblen(const char* _Nullable __s, size_t __n) __INTRODUCED_IN(26);
+#endif /* __BIONIC_AVAILABILITY_GUARD(26) */
+
 size_t mbstowcs(wchar_t* _Nullable __dst, const char* _Nullable __src, size_t __n);
 int mbtowc(wchar_t* _Nullable __wc_ptr, const char*  _Nullable __s, size_t __n);
 int wctomb(char* _Nullable __dst, wchar_t __wc);
diff --git a/libc/include/string.h b/libc/include/string.h
index 873ea82..79aac91 100644
--- a/libc/include/string.h
+++ b/libc/include/string.h
@@ -52,11 +52,11 @@
 int memcmp(const void* _Nonnull __lhs, const void* _Nonnull __rhs, size_t __n) __attribute_pure__;
 void* _Nonnull memcpy(void* _Nonnull, const void* _Nonnull, size_t);
 #if defined(__USE_GNU)
-// This conflicts with a polyfill in gettext-libintl
-// https://github.com/android/ndk/issues/2081
-#if __ANDROID_API__ >= 23
+
+#if __BIONIC_AVAILABILITY_GUARD(23)
 void* _Nonnull mempcpy(void* _Nonnull __dst, const void* _Nonnull __src, size_t __n) __INTRODUCED_IN(23);
-#endif
+#endif /* __BIONIC_AVAILABILITY_GUARD(23) */
+
 #endif
 void* _Nonnull memmove(void* _Nonnull __dst, const void* _Nonnull __src, size_t __n);
 
@@ -75,7 +75,11 @@
  *
  * Returns `dst`.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(34)
 void* _Nonnull memset_explicit(void* _Nonnull __dst, int __ch, size_t __n) __INTRODUCED_IN(34);
+#endif /* __BIONIC_AVAILABILITY_GUARD(34) */
+
 
 void* _Nullable memmem(const void* _Nonnull __haystack, size_t __haystack_size, const void* _Nonnull __needle, size_t __needle_size) __attribute_pure__;
 
@@ -83,10 +87,18 @@
 char* _Nullable __strchr_chk(const char* _Nonnull __s, int __ch, size_t __n);
 #if defined(__USE_GNU)
 #if defined(__cplusplus)
+
+#if __BIONIC_AVAILABILITY_GUARD(24)
 extern "C++" char* _Nonnull strchrnul(char* _Nonnull __s, int __ch) __RENAME(strchrnul) __attribute_pure__ __INTRODUCED_IN(24);
 extern "C++" const char* _Nonnull strchrnul(const char* _Nonnull __s, int __ch) __RENAME(strchrnul) __attribute_pure__ __INTRODUCED_IN(24);
+#endif /* __BIONIC_AVAILABILITY_GUARD(24) */
+
 #else
+
+#if __BIONIC_AVAILABILITY_GUARD(24)
 char* _Nonnull strchrnul(const char* _Nonnull __s, int __ch) __attribute_pure__ __INTRODUCED_IN(24);
+#endif /* __BIONIC_AVAILABILITY_GUARD(24) */
+
 #endif
 #endif
 
@@ -160,7 +172,11 @@
  * Available since API level 35.
  */
 #if defined(__USE_GNU)
+
+#if __BIONIC_AVAILABILITY_GUARD(35)
 const char* _Nullable strerrorname_np(int __errno_value) __INTRODUCED_IN(35);
+#endif /* __BIONIC_AVAILABILITY_GUARD(35) */
+
 #endif
 
 /**
@@ -203,10 +219,18 @@
  * It doesn't modify its argument, and in C++ it's const-correct.
  */
 #if defined(__cplusplus)
+
+#if __BIONIC_AVAILABILITY_GUARD(23)
 extern "C++" char* _Nonnull basename(char* _Nullable __path) __RENAME(__gnu_basename) __INTRODUCED_IN(23);
 extern "C++" const char* _Nonnull basename(const char* _Nonnull __path) __RENAME(__gnu_basename) __INTRODUCED_IN(23);
+#endif /* __BIONIC_AVAILABILITY_GUARD(23) */
+
 #else
+
+#if __BIONIC_AVAILABILITY_GUARD(23)
 char* _Nonnull basename(const char* _Nonnull __path) __RENAME(__gnu_basename) __INTRODUCED_IN(23);
+#endif /* __BIONIC_AVAILABILITY_GUARD(23) */
+
 #endif
 #endif
 
diff --git a/libc/include/sys/epoll.h b/libc/include/sys/epoll.h
index a5e3c14..bec7c64 100644
--- a/libc/include/sys/epoll.h
+++ b/libc/include/sys/epoll.h
@@ -88,13 +88,19 @@
  *
  * Available since API level 28.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(28)
 int epoll_pwait64(int __epoll_fd, struct epoll_event* _Nonnull __events, int __event_count, int __timeout_ms, const sigset64_t* _Nullable __mask) __INTRODUCED_IN(28);
+#endif /* __BIONIC_AVAILABILITY_GUARD(28) */
+
 
 /**
  * Like epoll_pwait() but with a `struct timespec` timeout, for nanosecond resolution.
  *
  * Available since API level 35.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(35)
 int epoll_pwait2(int __epoll_fd, struct epoll_event* _Nonnull __events, int __event_count, const struct timespec* _Nullable __timeout, const sigset_t* _Nullable __mask) __INTRODUCED_IN(35);
 
 /**
@@ -103,5 +109,7 @@
  * Available since API level 35.
  */
 int epoll_pwait2_64(int __epoll_fd, struct epoll_event* _Nonnull __events, int __event_count, const struct timespec* _Nullable __timeout, const sigset64_t* _Nullable __mask) __INTRODUCED_IN(35);
+#endif /* __BIONIC_AVAILABILITY_GUARD(35) */
+
 
 __END_DECLS
diff --git a/libc/include/sys/mman.h b/libc/include/sys/mman.h
index 1a0e7f6..38cbf2f 100644
--- a/libc/include/sys/mman.h
+++ b/libc/include/sys/mman.h
@@ -133,7 +133,11 @@
  *
  * Returns 0 on success, and returns -1 and sets `errno` on failure.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(30)
 int mlock2(const void* _Nonnull __addr, size_t __size, int __flags) __INTRODUCED_IN(30);
+#endif /* __BIONIC_AVAILABILITY_GUARD(30) */
+
 
 /**
  * [munlock(2)](https://man7.org/linux/man-pages/man2/munlock.2.html)
@@ -171,7 +175,11 @@
  *
  * Returns the number of bytes advised on success, and returns -1 and sets `errno` on failure.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(31)
 ssize_t process_madvise(int __pid_fd, const struct iovec* _Nonnull __iov, size_t __count, int __advice, unsigned __flags) __INTRODUCED_IN(31);
+#endif /* __BIONIC_AVAILABILITY_GUARD(31) */
+
 
 #if defined(__USE_GNU)
 
@@ -183,7 +191,11 @@
  *
  * Returns an fd on success, and returns -1 and sets `errno` on failure.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(30)
 int memfd_create(const char* _Nonnull __name, unsigned __flags) __INTRODUCED_IN(30);
+#endif /* __BIONIC_AVAILABILITY_GUARD(30) */
+
 
 #endif
 
@@ -220,7 +232,11 @@
  *
  * Returns 0 on success, and returns a positive error number on failure.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(23)
 int posix_madvise(void* _Nonnull __addr, size_t __size, int __advice) __INTRODUCED_IN(23);
+#endif /* __BIONIC_AVAILABILITY_GUARD(23) */
+
 
 /**
  * [mseal(2)](https://man7.org/linux/man-pages/man2/mseal.2.html)
@@ -232,6 +248,10 @@
  *
  * Returns 0 on success, and returns -1 and sets `errno` on failure.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(36)
 int mseal(void* _Nonnull __addr, size_t __size, unsigned long __flags) __INTRODUCED_IN(36);
+#endif /* __BIONIC_AVAILABILITY_GUARD(36) */
+
 
 __END_DECLS
diff --git a/libc/include/sys/msg.h b/libc/include/sys/msg.h
index 26071b1..8b619be 100644
--- a/libc/include/sys/msg.h
+++ b/libc/include/sys/msg.h
@@ -46,6 +46,8 @@
 typedef __kernel_ulong_t msglen_t;
 
 /** Not useful on Android; disallowed by SELinux. */
+
+#if __BIONIC_AVAILABILITY_GUARD(26)
 int msgctl(int __msg_id, int __op, struct msqid_ds* _Nullable __buf) __INTRODUCED_IN(26);
 /** Not useful on Android; disallowed by SELinux. */
 int msgget(key_t __key, int __flags) __INTRODUCED_IN(26);
@@ -53,5 +55,7 @@
 ssize_t msgrcv(int __msg_id, void* _Nonnull __msgbuf_ptr, size_t __size, long __type, int __flags) __INTRODUCED_IN(26);
 /** Not useful on Android; disallowed by SELinux. */
 int msgsnd(int __msg_id, const void* _Nonnull __msgbuf_ptr, size_t __size, int __flags) __INTRODUCED_IN(26);
+#endif /* __BIONIC_AVAILABILITY_GUARD(26) */
+
 
 __END_DECLS
diff --git a/libc/include/sys/pidfd.h b/libc/include/sys/pidfd.h
index 30455bb..aaf49c9 100644
--- a/libc/include/sys/pidfd.h
+++ b/libc/include/sys/pidfd.h
@@ -49,6 +49,8 @@
  *
  * Available since API level 31.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(31)
 int pidfd_open(pid_t __pid, unsigned int __flags) __INTRODUCED_IN(31);
 
 /**
@@ -72,5 +74,7 @@
  * Available since API level 31.
  */
 int pidfd_send_signal(int __pidfd, int __sig, siginfo_t * _Nullable __info, unsigned int __flags) __INTRODUCED_IN(31);
+#endif /* __BIONIC_AVAILABILITY_GUARD(31) */
+
 
 __END_DECLS
diff --git a/libc/include/sys/quota.h b/libc/include/sys/quota.h
index 6e32705..af09674 100644
--- a/libc/include/sys/quota.h
+++ b/libc/include/sys/quota.h
@@ -51,6 +51,10 @@
  *
  * Available since API level 26.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(26)
 int quotactl(int __op, const char* _Nullable __special, int __id, char* __BIONIC_COMPLICATED_NULLNESS __addr) __INTRODUCED_IN(26);
+#endif /* __BIONIC_AVAILABILITY_GUARD(26) */
+
 
 __END_DECLS
diff --git a/libc/include/sys/random.h b/libc/include/sys/random.h
index b4a9993..23d2c3a 100644
--- a/libc/include/sys/random.h
+++ b/libc/include/sys/random.h
@@ -52,6 +52,10 @@
  *
  * See also arc4random_buf() which is available in all API levels.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(28)
 __nodiscard ssize_t getrandom(void* _Nonnull __buffer, size_t __buffer_size, unsigned int __flags) __INTRODUCED_IN(28);
+#endif /* __BIONIC_AVAILABILITY_GUARD(28) */
+
 
 __END_DECLS
diff --git a/libc/include/sys/resource.h b/libc/include/sys/resource.h
index 6743343..05ef2c2 100644
--- a/libc/include/sys/resource.h
+++ b/libc/include/sys/resource.h
@@ -54,7 +54,11 @@
 
 int getrusage(int __who, struct rusage* _Nonnull __usage);
 
+
+#if (!defined(__LP64__) && __ANDROID_API__ >= 24) || (defined(__LP64__))
 int prlimit(pid_t __pid, int __resource, const struct rlimit* _Nullable __new_limit, struct rlimit* _Nullable __old_limit) __INTRODUCED_IN_32(24) __INTRODUCED_IN_64(21);
+#endif /* (!defined(__LP64__) && __ANDROID_API__ >= 24) || (defined(__LP64__)) */
+
 int prlimit64(pid_t __pid, int __resource, const struct rlimit64* _Nullable __new_limit, struct rlimit64* _Nullable __old_limit);
 
 __END_DECLS
diff --git a/libc/include/sys/select.h b/libc/include/sys/select.h
index d5b3495..a7227b0 100644
--- a/libc/include/sys/select.h
+++ b/libc/include/sys/select.h
@@ -119,6 +119,10 @@
  *
  * Available since API level 28.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(28)
 int pselect64(int __max_fd_plus_one, fd_set* _Nullable __read_fds, fd_set* _Nullable __write_fds, fd_set* _Nullable __exception_fds, const struct timespec* _Nullable __timeout, const sigset64_t* _Nullable __mask) __INTRODUCED_IN(28);
+#endif /* __BIONIC_AVAILABILITY_GUARD(28) */
+
 
 __END_DECLS
diff --git a/libc/include/sys/sem.h b/libc/include/sys/sem.h
index 5682282..72f567e 100644
--- a/libc/include/sys/sem.h
+++ b/libc/include/sys/sem.h
@@ -51,12 +51,20 @@
   void* _Nullable __pad;
 };
 
+
+#if __BIONIC_AVAILABILITY_GUARD(26)
 int semctl(int __sem_id, int __sem_num, int __op, ...) __INTRODUCED_IN(26);
 int semget(key_t __key, int __sem_count, int __flags) __INTRODUCED_IN(26);
 int semop(int __sem_id, struct sembuf* _Nonnull __ops, size_t __op_count) __INTRODUCED_IN(26);
+#endif /* __BIONIC_AVAILABILITY_GUARD(26) */
+
 
 #if defined(__USE_GNU)
+
+#if __BIONIC_AVAILABILITY_GUARD(26)
 int semtimedop(int __sem_id, struct sembuf* _Nonnull __ops, size_t __op_count, const struct timespec* _Nullable __timeout) __INTRODUCED_IN(26);
+#endif /* __BIONIC_AVAILABILITY_GUARD(26) */
+
 #endif
 
 __END_DECLS
diff --git a/libc/include/sys/shm.h b/libc/include/sys/shm.h
index 8ab3d9a..a960781 100644
--- a/libc/include/sys/shm.h
+++ b/libc/include/sys/shm.h
@@ -48,6 +48,8 @@
 typedef unsigned long shmatt_t;
 
 /** Not useful on Android; disallowed by SELinux. */
+
+#if __BIONIC_AVAILABILITY_GUARD(26)
 void* _Nonnull shmat(int __shm_id, const void* _Nullable __addr, int __flags) __INTRODUCED_IN(26);
 /** Not useful on Android; disallowed by SELinux. */
 int shmctl(int __shm_id, int __op, struct shmid_ds* _Nullable __buf) __INTRODUCED_IN(26);
@@ -55,5 +57,7 @@
 int shmdt(const void* _Nonnull __addr) __INTRODUCED_IN(26);
 /** Not useful on Android; disallowed by SELinux. */
 int shmget(key_t __key, size_t __size, int __flags) __INTRODUCED_IN(26);
+#endif /* __BIONIC_AVAILABILITY_GUARD(26) */
+
 
 __END_DECLS
diff --git a/libc/include/sys/signalfd.h b/libc/include/sys/signalfd.h
index 5568b7d..eaea525 100644
--- a/libc/include/sys/signalfd.h
+++ b/libc/include/sys/signalfd.h
@@ -51,6 +51,10 @@
 /**
  * Like signalfd() but allows setting a signal mask with RT signals even from a 32-bit process.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(28)
 int signalfd64(int __fd, const sigset64_t* _Nonnull __mask, int __flags) __INTRODUCED_IN(28);
+#endif /* __BIONIC_AVAILABILITY_GUARD(28) */
+
 
 __END_DECLS
diff --git a/libc/include/sys/stat.h b/libc/include/sys/stat.h
index ed52bcc..0b4b248 100644
--- a/libc/include/sys/stat.h
+++ b/libc/include/sys/stat.h
@@ -177,7 +177,11 @@
  *
  * Returns 0 on success and returns -1 and sets `errno` on failure.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(36)
 int lchmod(const char* _Nonnull __path, mode_t __mode) __INTRODUCED_IN(36);
+#endif /* __BIONIC_AVAILABILITY_GUARD(36) */
+
 
 /**
  * [mkdir(2)](https://man7.org/linux/man-pages/man2/mkdir.2.html)
@@ -281,7 +285,11 @@
  *
  * Returns 0 on success and returns -1 and sets `errno` on failure.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(23)
 int mkfifoat(int __dir_fd, const char* _Nonnull __path, mode_t __mode) __INTRODUCED_IN(23);
+#endif /* __BIONIC_AVAILABILITY_GUARD(23) */
+
 
 /**
  * Used in the tv_nsec field of an argument to utimensat()/futimens()
@@ -332,7 +340,11 @@
  *
  * Available since API level 30.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(30)
 int statx(int __dir_fd, const char* _Nullable __path, int __flags, unsigned __mask, struct statx* _Nonnull __buf) __INTRODUCED_IN(30);
+#endif /* __BIONIC_AVAILABILITY_GUARD(30) */
+
 #endif
 
 __END_DECLS
diff --git a/libc/include/sys/sysinfo.h b/libc/include/sys/sysinfo.h
index 5956feb..ed6a007 100644
--- a/libc/include/sys/sysinfo.h
+++ b/libc/include/sys/sysinfo.h
@@ -53,6 +53,8 @@
  *
  * See also sysconf().
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(23)
 int get_nprocs_conf(void) __INTRODUCED_IN(23);
 
 /**
@@ -84,5 +86,7 @@
  * See also sysconf().
  */
 long get_avphys_pages(void) __INTRODUCED_IN(23);
+#endif /* __BIONIC_AVAILABILITY_GUARD(23) */
+
 
 __END_DECLS
diff --git a/libc/include/sys/system_properties.h b/libc/include/sys/system_properties.h
index e8b6e34..1303079 100644
--- a/libc/include/sys/system_properties.h
+++ b/libc/include/sys/system_properties.h
@@ -71,9 +71,13 @@
  *
  * Available since API level 26.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(26)
 void __system_property_read_callback(const prop_info* _Nonnull __pi,
     void (* _Nonnull __callback)(void* _Nullable __cookie, const char* _Nonnull __name, const char* _Nonnull __value, uint32_t __serial),
     void* _Nullable __cookie) __INTRODUCED_IN(26);
+#endif /* __BIONIC_AVAILABILITY_GUARD(26) */
+
 
 /**
  * Passes a `prop_info` for each system property to the provided
@@ -101,8 +105,12 @@
  * Available since API level 26.
  */
 struct timespec;
+
+#if __BIONIC_AVAILABILITY_GUARD(26)
 bool __system_property_wait(const prop_info* _Nullable __pi, uint32_t __old_serial, uint32_t* _Nonnull __new_serial_ptr, const struct timespec* _Nullable __relative_timeout)
     __INTRODUCED_IN(26);
+#endif /* __BIONIC_AVAILABILITY_GUARD(26) */
+
 
 /**
  * Deprecated: there's no limit on the length of a property name since
@@ -233,7 +241,11 @@
  *
  * Available since API level 35.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(35)
 int __system_properties_zygote_reload(void) __INTRODUCED_IN(35);
+#endif /* __BIONIC_AVAILABILITY_GUARD(35) */
+
 
 /**
  * Deprecated: previously for testing, but now that SystemProperties is its own
diff --git a/libc/include/sys/thread_properties.h b/libc/include/sys/thread_properties.h
index efd212a..b6214ee 100644
--- a/libc/include/sys/thread_properties.h
+++ b/libc/include/sys/thread_properties.h
@@ -50,6 +50,8 @@
  *
  * Available since API level 31.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(31)
 void __libc_get_static_tls_bounds(void* _Nonnull * _Nonnull __static_tls_begin,
                                   void* _Nonnull * _Nonnull __static_tls_end) __INTRODUCED_IN(31);
 
@@ -93,5 +95,7 @@
                           void* _Nonnull __dynamic_tls_end),
     void (* _Nonnull __on_destruction)(void* _Nonnull __dynamic_tls_begin,
                              void* _Nonnull __dynamic_tls_end)) __INTRODUCED_IN(31);
+#endif /* __BIONIC_AVAILABILITY_GUARD(31) */
+
 
 __END_DECLS
diff --git a/libc/include/sys/time.h b/libc/include/sys/time.h
index 6ba7a37..d12c306 100644
--- a/libc/include/sys/time.h
+++ b/libc/include/sys/time.h
@@ -47,8 +47,12 @@
 int utimes(const char* _Nonnull __path, const struct timeval __times[_Nullable 2]);
 
 #if defined(__USE_BSD)
+
+#if __BIONIC_AVAILABILITY_GUARD(26)
 int futimes(int __fd, const struct timeval __times[_Nullable 2]) __INTRODUCED_IN(26);
 int lutimes(const char* _Nonnull __path, const struct timeval __times[_Nullable 2]) __INTRODUCED_IN(26);
+#endif /* __BIONIC_AVAILABILITY_GUARD(26) */
+
 #endif
 
 #if defined(__USE_GNU)
@@ -65,7 +69,11 @@
  *
  * Available since API level 26.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(26)
 int futimesat(int __dir_fd, const char* __BIONIC_COMPLICATED_NULLNESS __path, const struct timeval __times[_Nullable 2]) __INTRODUCED_IN(26);
+#endif /* __BIONIC_AVAILABILITY_GUARD(26) */
+
 #endif
 
 #define timerclear(a)   \
diff --git a/libc/include/sys/timex.h b/libc/include/sys/timex.h
index 828eb47..6fb58e4 100644
--- a/libc/include/sys/timex.h
+++ b/libc/include/sys/timex.h
@@ -46,6 +46,8 @@
  *
  * Available since API level 24.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(24)
 int adjtimex(struct timex* _Nonnull __buf) __INTRODUCED_IN(24);
 
 /**
@@ -56,5 +58,7 @@
  * Available since API level 24.
  */
 int clock_adjtime(clockid_t __clock, struct timex* _Nonnull __tx) __INTRODUCED_IN(24);
+#endif /* __BIONIC_AVAILABILITY_GUARD(24) */
+
 
 __END_DECLS
diff --git a/libc/include/sys/uio.h b/libc/include/sys/uio.h
index d3e6561..eff3b14 100644
--- a/libc/include/sys/uio.h
+++ b/libc/include/sys/uio.h
@@ -69,6 +69,8 @@
  *
  * Available since API level 24.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(24)
 ssize_t preadv(int __fd, const struct iovec* _Nonnull __iov, int __count, off_t __offset) __RENAME_IF_FILE_OFFSET64(preadv64) __INTRODUCED_IN(24);
 
 /**
@@ -96,6 +98,8 @@
  * Available since API level 24.
  */
 ssize_t pwritev64(int __fd, const struct iovec* _Nonnull __iov, int __count, off64_t __offset) __INTRODUCED_IN(24);
+#endif /* __BIONIC_AVAILABILITY_GUARD(24) */
+
 
 /**
  * [preadv2(2)](https://man7.org/linux/man-pages/man2/preadv2.2.html) reads
@@ -107,6 +111,8 @@
  *
  * Available since API level 33.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(33)
 ssize_t preadv2(int __fd, const struct iovec* _Nonnull __iov, int __count, off_t __offset, int __flags) __RENAME_IF_FILE_OFFSET64(preadv64v2) __INTRODUCED_IN(33);
 
 /**
@@ -134,6 +140,8 @@
  * Available since API level 33.
  */
 ssize_t pwritev64v2(int __fd, const struct iovec* _Nonnull __iov, int __count, off64_t __offset, int __flags) __INTRODUCED_IN(33);
+#endif /* __BIONIC_AVAILABILITY_GUARD(33) */
+
 
 /**
  * [process_vm_readv(2)](https://man7.org/linux/man-pages/man2/process_vm_readv.2.html)
@@ -144,6 +152,8 @@
  *
  * Available since API level 23.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(23)
 ssize_t process_vm_readv(pid_t __pid, const struct iovec* __BIONIC_COMPLICATED_NULLNESS __local_iov, unsigned long __local_iov_count, const struct iovec* __BIONIC_COMPLICATED_NULLNESS __remote_iov, unsigned long __remote_iov_count, unsigned long __flags) __INTRODUCED_IN(23);
 
 /**
@@ -156,6 +166,8 @@
  * Available since API level 23.
  */
 ssize_t process_vm_writev(pid_t __pid, const struct iovec* __BIONIC_COMPLICATED_NULLNESS __local_iov, unsigned long __local_iov_count, const struct iovec* __BIONIC_COMPLICATED_NULLNESS __remote_iov, unsigned long __remote_iov_count, unsigned long __flags) __INTRODUCED_IN(23);
+#endif /* __BIONIC_AVAILABILITY_GUARD(23) */
+
 
 #endif
 
diff --git a/libc/include/time.h b/libc/include/time.h
index e9d6569..6c9b761 100644
--- a/libc/include/time.h
+++ b/libc/include/time.h
@@ -166,7 +166,11 @@
  *
  * Available since API level 35.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(35)
 time_t mktime_z(timezone_t _Nonnull __tz, struct tm* _Nonnull __tm) __INTRODUCED_IN(35);
+#endif /* __BIONIC_AVAILABILITY_GUARD(35) */
+
 
 /**
  * [localtime(3)](https://man7.org/linux/man-pages/man3/localtime.3p.html) converts
@@ -200,7 +204,11 @@
  *
  * Available since API level 35.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(35)
 struct tm* _Nullable localtime_rz(timezone_t _Nonnull __tz, const time_t* _Nonnull __t, struct tm* _Nonnull __tm) __INTRODUCED_IN(35);
+#endif /* __BIONIC_AVAILABILITY_GUARD(35) */
+
 
 /**
  * Inverse of localtime().
@@ -314,6 +322,8 @@
  *
  * Available since API level 35.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(35)
 timezone_t _Nullable tzalloc(const char* _Nullable __id) __INTRODUCED_IN(35);
 
 /**
@@ -326,6 +336,8 @@
  * Available since API level 35.
  */
 void tzfree(timezone_t _Nullable __tz) __INTRODUCED_IN(35);
+#endif /* __BIONIC_AVAILABILITY_GUARD(35) */
+
 
 /**
  * [clock(3)](https://man7.org/linux/man-pages/man3/clock.3.html)
@@ -345,7 +357,11 @@
  *
  * Returns 0 on success, and returns -1 and returns an error number on failure.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(23)
 int clock_getcpuclockid(pid_t __pid, clockid_t* _Nonnull __clock) __INTRODUCED_IN(23);
+#endif /* __BIONIC_AVAILABILITY_GUARD(23) */
+
 
 /**
  * [clock_getres(2)](https://man7.org/linux/man-pages/man2/clock_getres.2.html)
@@ -459,7 +475,11 @@
  * Available since API level 29 for TIME_UTC; other bases arrived later.
  * Code for Android should prefer clock_gettime().
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(29)
 int timespec_get(struct timespec* _Nonnull __ts, int __base) __INTRODUCED_IN(29);
+#endif /* __BIONIC_AVAILABILITY_GUARD(29) */
+
 
 /**
  * timespec_getres(3) is equivalent to clock_getres() for the clock corresponding to the given base.
@@ -469,6 +489,10 @@
  * Available since API level 35.
  * Code for Android should prefer clock_gettime().
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(35)
 int timespec_getres(struct timespec* _Nonnull __ts, int __base) __INTRODUCED_IN(35);
+#endif /* __BIONIC_AVAILABILITY_GUARD(35) */
+
 
 __END_DECLS
diff --git a/libc/include/unistd.h b/libc/include/unistd.h
index f11990d..e623339 100644
--- a/libc/include/unistd.h
+++ b/libc/include/unistd.h
@@ -101,7 +101,11 @@
  *
  * Available since API level 35.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(35)
 pid_t _Fork(void) __INTRODUCED_IN(35);
+#endif /* __BIONIC_AVAILABILITY_GUARD(35) */
+
 
 /**
  * [vfork(2)](https://man7.org/linux/man-pages/man2/vfork.2.html) creates a new
@@ -146,7 +150,11 @@
 int execlp(const char* _Nonnull __file, const char* _Nullable __arg0, ...) __attribute__((__sentinel__));
 int execle(const char* _Nonnull __path, const char* _Nullable __arg0, ... /*,  char* const* __envp */)
     __attribute__((__sentinel__(1)));
+
+#if __BIONIC_AVAILABILITY_GUARD(28)
 int fexecve(int __fd, char* _Nullable const* _Nullable __argv, char* _Nullable const* _Nullable __envp) __INTRODUCED_IN(28);
+#endif /* __BIONIC_AVAILABILITY_GUARD(28) */
+
 
 int nice(int __incr);
 
@@ -247,7 +255,11 @@
 int getresuid(uid_t* _Nonnull __ruid, uid_t* _Nonnull __euid, uid_t* _Nonnull __suid);
 int getresgid(gid_t* _Nonnull __rgid, gid_t* _Nonnull __egid, gid_t* _Nonnull __sgid);
 char* _Nullable getlogin(void);
+
+#if __BIONIC_AVAILABILITY_GUARD(28)
 int getlogin_r(char* _Nonnull __buffer, size_t __buffer_size) __INTRODUCED_IN(28);
+#endif /* __BIONIC_AVAILABILITY_GUARD(28) */
+
 
 long fpathconf(int __fd, int __name);
 long pathconf(const char* _Nonnull __path, int __name);
@@ -299,7 +311,11 @@
 
 void sync(void);
 #if defined(__USE_GNU)
+
+#if __BIONIC_AVAILABILITY_GUARD(28)
 int syncfs(int __fd) __INTRODUCED_IN(28);
+#endif /* __BIONIC_AVAILABILITY_GUARD(28) */
+
 #endif
 
 int close(int __fd);
@@ -361,7 +377,11 @@
 int usleep(useconds_t __microseconds);
 
 int gethostname(char* _Nonnull _buf, size_t __buf_size);
+
+#if __BIONIC_AVAILABILITY_GUARD(23)
 int sethostname(const char* _Nonnull __name, size_t __n) __INTRODUCED_IN(23);
+#endif /* __BIONIC_AVAILABILITY_GUARD(23) */
+
 
 int brk(void* _Nonnull __addr);
 void* _Nullable sbrk(ptrdiff_t __increment);
@@ -404,8 +424,12 @@
     } while (_rc == -1 && errno == EINTR); \
     _rc; })
 
+
+#if __BIONIC_AVAILABILITY_GUARD(26)
 int getdomainname(char* _Nonnull __buf, size_t __buf_size) __INTRODUCED_IN(26);
 int setdomainname(const char* _Nonnull __name, size_t __n) __INTRODUCED_IN(26);
+#endif /* __BIONIC_AVAILABILITY_GUARD(26) */
+
 
 /**
  * [copy_file_range(2)](https://man7.org/linux/man-pages/man2/copy_file_range.2.html) copies
@@ -416,7 +440,11 @@
  * Returns the number of bytes copied on success, and returns -1 and sets
  * `errno` on failure.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(34)
 ssize_t copy_file_range(int __fd_in, off64_t* _Nullable __off_in, int __fd_out, off64_t* _Nullable __off_out, size_t __length, unsigned int __flags) __INTRODUCED_IN(34);
+#endif /* __BIONIC_AVAILABILITY_GUARD(34) */
+
 
 #if __ANDROID_API__ >= 28
 void swab(const void* _Nonnull __src, void* _Nonnull __dst, ssize_t __byte_count) __INTRODUCED_IN(28);
@@ -436,7 +464,11 @@
  *
  * Returns 0 on success, and returns -1 and sets `errno` on failure.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(34)
 int close_range(unsigned int __min_fd, unsigned int __max_fd, int __flags) __INTRODUCED_IN(34);
+#endif /* __BIONIC_AVAILABILITY_GUARD(34) */
+
 
 #if defined(__BIONIC_INCLUDE_FORTIFY_HEADERS)
 #define _UNISTD_H_
diff --git a/libc/include/utmp.h b/libc/include/utmp.h
index d249f8a..1674491 100644
--- a/libc/include/utmp.h
+++ b/libc/include/utmp.h
@@ -131,6 +131,10 @@
  *
  * Available since API level 23.
  */
+
+#if __BIONIC_AVAILABILITY_GUARD(23)
 int login_tty(int __fd) __INTRODUCED_IN(23);
+#endif /* __BIONIC_AVAILABILITY_GUARD(23) */
+
 
 __END_DECLS
diff --git a/libc/include/wchar.h b/libc/include/wchar.h
index e86f94d..56594dc 100644
--- a/libc/include/wchar.h
+++ b/libc/include/wchar.h
@@ -75,7 +75,11 @@
 wchar_t* _Nonnull wcpncpy(wchar_t* _Nonnull __dst, const wchar_t* _Nonnull __src, size_t __n);
 size_t wcrtomb(char* _Nullable __buf, wchar_t __wc, mbstate_t* _Nullable __ps);
 int wcscasecmp(const wchar_t* _Nonnull __lhs, const wchar_t* _Nonnull __rhs);
+
+#if __BIONIC_AVAILABILITY_GUARD(23)
 int wcscasecmp_l(const wchar_t* _Nonnull __lhs, const wchar_t* _Nonnull __rhs, locale_t _Nonnull __l) __INTRODUCED_IN(23);
+#endif /* __BIONIC_AVAILABILITY_GUARD(23) */
+
 wchar_t* _Nonnull wcscat(wchar_t* _Nonnull __dst, const wchar_t* _Nonnull __src);
 wchar_t* _Nullable wcschr(const wchar_t * _Nonnull __s, wchar_t __wc);
 int wcscmp(const wchar_t* _Nonnull __lhs, const wchar_t* _Nonnull __rhs);
@@ -83,10 +87,18 @@
 wchar_t* _Nonnull wcscpy(wchar_t* _Nonnull __dst, const wchar_t* _Nonnull __src);
 size_t wcscspn(const wchar_t* _Nonnull __s, const wchar_t* _Nonnull __accept);
 size_t wcsftime(wchar_t* _Nonnull __buf, size_t __n, const wchar_t* _Nullable __fmt, const struct tm* _Nonnull __tm);
+
+#if __BIONIC_AVAILABILITY_GUARD(28)
 size_t wcsftime_l(wchar_t* _Nonnull __buf, size_t __n, const wchar_t* _Nullable __fmt, const struct tm* _Nonnull __tm, locale_t _Nonnull __l) __INTRODUCED_IN(28);
+#endif /* __BIONIC_AVAILABILITY_GUARD(28) */
+
 size_t wcslen(const wchar_t* _Nonnull __s);
 int wcsncasecmp(const wchar_t* _Nonnull __lhs, const wchar_t* _Nonnull __rhs, size_t __n);
+
+#if __BIONIC_AVAILABILITY_GUARD(23)
 int wcsncasecmp_l(const wchar_t* _Nonnull __lhs, const wchar_t* _Nonnull __rhs, size_t __n, locale_t _Nonnull __l) __INTRODUCED_IN(23);
+#endif /* __BIONIC_AVAILABILITY_GUARD(23) */
+
 wchar_t* _Nonnull wcsncat(wchar_t* _Nonnull __dst, const wchar_t* _Nonnull __src, size_t __n);
 int wcsncmp(const wchar_t* _Nonnull __lhs, const wchar_t* _Nonnull __rhs, size_t __n);
 wchar_t* _Nonnull wcsncpy(wchar_t* _Nonnull __dst, const wchar_t* _Nonnull __src, size_t __n);
@@ -117,7 +129,11 @@
 int wmemcmp(const wchar_t* _Nullable __lhs, const wchar_t* _Nullable __rhs, size_t __n);
 wchar_t* _Nonnull wmemcpy(wchar_t* _Nonnull __dst, const wchar_t* _Nonnull __src, size_t __n);
 #if defined(__USE_GNU)
+
+#if __BIONIC_AVAILABILITY_GUARD(23)
 wchar_t* _Nonnull wmempcpy(wchar_t* _Nonnull __dst, const wchar_t* _Nonnull __src, size_t __n) __INTRODUCED_IN(23);
+#endif /* __BIONIC_AVAILABILITY_GUARD(23) */
+
 #endif
 wchar_t* _Nonnull wmemmove(wchar_t* _Nonnull __dst, const wchar_t* _Nonnull __src, size_t __n);
 wchar_t* _Nonnull wmemset(wchar_t* _Nonnull __dst, wchar_t __wc, size_t __n);
@@ -133,7 +149,11 @@
 size_t wcslcat(wchar_t* _Nonnull __dst, const wchar_t* _Nonnull __src, size_t __n);
 size_t wcslcpy(wchar_t* _Nonnull __dst, const wchar_t* _Nonnull __src, size_t __n);
 
+
+#if __BIONIC_AVAILABILITY_GUARD(23)
 FILE* _Nullable open_wmemstream(wchar_t* _Nonnull * _Nonnull __ptr, size_t* _Nonnull  __size_ptr) __INTRODUCED_IN(23);
+#endif /* __BIONIC_AVAILABILITY_GUARD(23) */
+
 wchar_t* _Nullable wcsdup(const wchar_t* _Nonnull __s);
 size_t wcsnlen(const wchar_t* _Nonnull __s, size_t __n);
 
diff --git a/libc/include/wctype.h b/libc/include/wctype.h
index 2b7f972..30ec04f 100644
--- a/libc/include/wctype.h
+++ b/libc/include/wctype.h
@@ -52,8 +52,12 @@
 wint_t towlower_l(wint_t __wc, locale_t _Nonnull __l);
 wint_t towupper_l(wint_t __wc, locale_t _Nonnull __l);
 
+
+#if __BIONIC_AVAILABILITY_GUARD(26)
 wint_t towctrans_l(wint_t __wc, wctrans_t _Nonnull __transform, locale_t _Nonnull __l) __INTRODUCED_IN(26);
 wctrans_t _Nonnull wctrans_l(const char* _Nonnull __name, locale_t _Nonnull __l) __INTRODUCED_IN(26);
+#endif /* __BIONIC_AVAILABILITY_GUARD(26) */
+
 
 wctype_t wctype_l(const char* _Nonnull __name, locale_t _Nonnull __l);
 int iswctype_l(wint_t __wc, wctype_t __transform, locale_t _Nonnull __l);