diff --git a/libc/bionic/libc_init_dynamic.cpp b/libc/bionic/libc_init_dynamic.cpp
index 6b2d86f..fc68b8a 100644
--- a/libc/bionic/libc_init_dynamic.cpp
+++ b/libc/bionic/libc_init_dynamic.cpp
@@ -137,9 +137,3 @@
                  args.argv + __libc_shared_globals->initial_linker_arg_count,
                  args.envp));
 }
-
-extern "C" int android_get_application_target_sdk_version();
-
-int bionic_get_application_target_sdk_version() {
-  return android_get_application_target_sdk_version();
-}
diff --git a/libc/bionic/libc_init_static.cpp b/libc/bionic/libc_init_static.cpp
index a54840b..ef1c393 100644
--- a/libc/bionic/libc_init_static.cpp
+++ b/libc/bionic/libc_init_static.cpp
@@ -152,10 +152,6 @@
   return g_target_sdk_version;
 }
 
-int bionic_get_application_target_sdk_version() {
-  return android_get_application_target_sdk_version();
-}
-
 extern "C" void android_set_application_target_sdk_version(int target) {
   g_target_sdk_version = target;
 }
diff --git a/libc/bionic/pthread_internal.cpp b/libc/bionic/pthread_internal.cpp
index 92786fe..2b7a99a 100644
--- a/libc/bionic/pthread_internal.cpp
+++ b/libc/bionic/pthread_internal.cpp
@@ -36,7 +36,6 @@
 #include <async_safe/log.h>
 
 #include "private/bionic_futex.h"
-#include "private/bionic_sdk_version.h"
 #include "private/bionic_tls.h"
 
 static pthread_internal_t* g_thread_list = nullptr;
@@ -114,7 +113,7 @@
   }
 
   // Historically we'd return null, but
-  if (bionic_get_application_target_sdk_version() >= __ANDROID_API_O__) {
+  if (android_get_application_target_sdk_version() >= __ANDROID_API_O__) {
     if (thread == nullptr) {
       // This seems to be a common mistake, and it's relatively harmless because
       // there will never be a valid thread at address 0, whereas other invalid
diff --git a/libc/bionic/pthread_mutex.cpp b/libc/bionic/pthread_mutex.cpp
index fda0b93..d9ddf10 100644
--- a/libc/bionic/pthread_mutex.cpp
+++ b/libc/bionic/pthread_mutex.cpp
@@ -42,7 +42,6 @@
 #include "private/bionic_constants.h"
 #include "private/bionic_fortify.h"
 #include "private/bionic_futex.h"
-#include "private/bionic_sdk_version.h"
 #include "private/bionic_systrace.h"
 #include "private/bionic_time_conversions.h"
 #include "private/bionic_tls.h"
@@ -789,7 +788,7 @@
 // ARM64. So make it noinline.
 static int __attribute__((noinline)) HandleUsingDestroyedMutex(pthread_mutex_t* mutex,
                                                                const char* function_name) {
-    if (bionic_get_application_target_sdk_version() >= __ANDROID_API_P__) {
+    if (android_get_application_target_sdk_version() >= __ANDROID_API_P__) {
         __fortify_fatal("%s called on a destroyed mutex (%p)", function_name, mutex);
     }
     return EBUSY;
diff --git a/libc/bionic/semaphore.cpp b/libc/bionic/semaphore.cpp
index d401b66..e0486b4 100644
--- a/libc/bionic/semaphore.cpp
+++ b/libc/bionic/semaphore.cpp
@@ -41,7 +41,6 @@
 
 #include "private/bionic_constants.h"
 #include "private/bionic_futex.h"
-#include "private/bionic_sdk_version.h"
 #include "private/bionic_time_conversions.h"
 
 // In this implementation, a semaphore contains a
@@ -222,7 +221,7 @@
     }
 
     int result = __futex_wait_ex(sem_count_ptr, shared, shared | SEMCOUNT_MINUS_ONE, false, nullptr);
-    if (bionic_get_application_target_sdk_version() >= __ANDROID_API_N__) {
+    if (android_get_application_target_sdk_version() >= __ANDROID_API_N__) {
       if (result ==-EINTR) {
         errno = EINTR;
         return -1;
diff --git a/libc/include/android/api-level.h b/libc/include/android/api-level.h
index 3a8f926..d1d1aea 100644
--- a/libc/include/android/api-level.h
+++ b/libc/include/android/api-level.h
@@ -35,6 +35,8 @@
 
 #include <sys/cdefs.h>
 
+__BEGIN_DECLS
+
 #ifndef __ANDROID_API_FUTURE__
 /**
  * Magic version number for an Android OS build which has
@@ -97,3 +99,39 @@
 
 /** Names the "Q" API level (29), for comparisons against __ANDROID_API__. */
 #define __ANDROID_API_Q__ 29
+
+/**
+ * Returns the `targetSdkVersion` of the caller, or `__ANDROID_API_FUTURE__`
+ * if there is no known target SDK version (for code not running in the
+ * context of an app).
+ *
+ * The returned values correspond to the named constants in `<android/api-level.h>`,
+ * and is equivalent to the AndroidManifest.xml `targetSdkVersion`.
+ *
+ * See also android_get_device_api_level().
+ *
+ * Available since API level 24.
+ */
+int android_get_application_target_sdk_version() __INTRODUCED_IN(24);
+
+#if __ANDROID_API__ < __ANDROID_API_Q__
+
+// android_get_application_target_sdk_version is a static inline before API level 29.
+#define __BIONIC_GET_DEVICE_API_LEVEL_INLINE static __inline
+#include <bits/get_device_api_level_inlines.h>
+#undef __BIONIC_GET_DEVICE_API_LEVEL_INLINE
+
+#else
+
+/**
+ * Returns the API level of the device we're actually running on, or -1 on failure.
+ * The returned values correspond to the named constants in `<android/api-level.h>`,
+ * and is equivalent to the Java `Build.VERSION.SDK_INT` API.
+ *
+ * See also android_get_application_target_sdk_version().
+ */
+int android_get_device_api_level() __INTRODUCED_IN(29);
+
+#endif
+
+__END_DECLS
diff --git a/libc/include/android/get_device_api_level.h b/libc/include/android/get_device_api_level.h
deleted file mode 100644
index 39609da..0000000
--- a/libc/include/android/get_device_api_level.h
+++ /dev/null
@@ -1,54 +0,0 @@
-/*
- * Copyright (C) 2018 The Android Open Source Project
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- *  * Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer.
- *  * Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in
- *    the documentation and/or other materials provided with the
- *    distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
- * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
- * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
- * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
- * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
- * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
- * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
- * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
- * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- */
-
-#pragma once
-
-/**
- * @file android/get_device_api_level.h
- * @brief Check the API level of the device we're actually running on.
- */
-
-#include <sys/cdefs.h>
-
-__BEGIN_DECLS
-
-#if __ANDROID_API__ >= __ANDROID_API_Q__
-// This file is implemented as static inlines before API level 29.
-
-/**
- * Returns the API level of the device we're actually running on, or -1 on failure.
- * The returned values correspond to the named constants in <android/api-level.h>,
- * and is equivalent to the Java `Build.VERSION.SDK_INT` API.
- */
-int android_get_device_api_level() __INTRODUCED_IN(29);
-
-#endif
-
-__END_DECLS
-
-#include <android/legacy_get_device_api_level_inlines.h>
diff --git a/libc/include/android/legacy_get_device_api_level_inlines.h b/libc/include/android/legacy_get_device_api_level_inlines.h
deleted file mode 100644
index b60123c..0000000
--- a/libc/include/android/legacy_get_device_api_level_inlines.h
+++ /dev/null
@@ -1,38 +0,0 @@
-/*
- * Copyright (C) 2018 The Android Open Source Project
- * All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- *  * Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer.
- *  * Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in
- *    the documentation and/or other materials provided with the
- *    distribution.
- *
- * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
- * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
- * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
- * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
- * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
- * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
- * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
- * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
- * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- */
-
-#pragma once
-
-#include <sys/cdefs.h>
-
-#if __ANDROID_API__ < __ANDROID_API_Q__
-
-#define __BIONIC_GET_DEVICE_API_LEVEL_INLINE static __inline
-#include <bits/get_device_api_level_inlines.h>
-
-#endif
diff --git a/libc/include/android/versioning.h b/libc/include/android/versioning.h
index 6e4b8ab..01fa348 100644
--- a/libc/include/android/versioning.h
+++ b/libc/include/android/versioning.h
@@ -14,23 +14,16 @@
  * limitations under the License.
  */
 
-#ifndef ANDROID_VERSIONING_H
-#define ANDROID_VERSIONING_H
+#pragma once
 
-#ifndef __STRING
-#define __STRING(x) #x
-#endif
-
-#define __INTRODUCED_IN(api_level) __attribute__((annotate("introduced_in=" __STRING(api_level))))
+#define __INTRODUCED_IN(api_level) __attribute__((annotate("introduced_in=" #api_level)))
 #define __INTRODUCED_IN_FUTURE __attribute__((annotate("introduced_in_future")))
-#define __DEPRECATED_IN(api_level) __attribute__((annotate("deprecated_in=" __STRING(api_level))))
-#define __REMOVED_IN(api_level) __attribute__((annotate("obsoleted_in=" __STRING(api_level))))
-#define __INTRODUCED_IN_32(api_level) __attribute__((annotate("introduced_in_32=" __STRING(api_level))))
-#define __INTRODUCED_IN_64(api_level) __attribute__((annotate("introduced_in_64=" __STRING(api_level))))
-#define __INTRODUCED_IN_ARM(api_level) __attribute__((annotate("introduced_in_arm=" __STRING(api_level))))
-#define __INTRODUCED_IN_X86(api_level) __attribute__((annotate("introduced_in_x86=" __STRING(api_level))))
-#define __INTRODUCED_IN_MIPS(api_level) __attribute__((annotate("introduced_in_mips=" __STRING(api_level))))
+#define __DEPRECATED_IN(api_level) __attribute__((annotate("deprecated_in=" #api_level)))
+#define __REMOVED_IN(api_level) __attribute__((annotate("obsoleted_in=" #api_level)))
+#define __INTRODUCED_IN_32(api_level) __attribute__((annotate("introduced_in_32=" #api_level)))
+#define __INTRODUCED_IN_64(api_level) __attribute__((annotate("introduced_in_64=" #api_level)))
+#define __INTRODUCED_IN_ARM(api_level) __attribute__((annotate("introduced_in_arm=" #api_level)))
+#define __INTRODUCED_IN_X86(api_level) __attribute__((annotate("introduced_in_x86=" #api_level)))
+#define __INTRODUCED_IN_MIPS(api_level) __attribute__((annotate("introduced_in_mips=" #api_level)))
 
 #define __VERSIONER_NO_GUARD __attribute__((annotate("versioner_no_guard")))
-
-#endif /* ANDROID_VERSIONING_H */
diff --git a/libc/include/bits/get_device_api_level_inlines.h b/libc/include/bits/get_device_api_level_inlines.h
index 8e17814..9c6e243 100644
--- a/libc/include/bits/get_device_api_level_inlines.h
+++ b/libc/include/bits/get_device_api_level_inlines.h
@@ -28,18 +28,20 @@
 
 #pragma once
 
-#include <stdlib.h>
 #include <sys/cdefs.h>
-#include <sys/system_properties.h>
 
 #if !defined(__BIONIC_GET_DEVICE_API_LEVEL_INLINE)
-#define __BIONIC_GET_DEVICE_API_LEVEL_INLINE static __inline
+#define __BIONIC_GET_DEVICE_API_LEVEL_INLINE static inline /* for versioner */
 #endif
 
 __BEGIN_DECLS
 
+// Avoid circular dependencies since this is exposed from <sys/cdefs.h>.
+int __system_property_get(const char* __name, char* __value);
+int atoi(const char* __s) __attribute_pure__;
+
 __BIONIC_GET_DEVICE_API_LEVEL_INLINE int android_get_device_api_level() {
-  char value[PROP_VALUE_MAX] = { 0 };
+  char value[92] = { 0 };
   if (__system_property_get("ro.build.version.sdk", value) < 1) return -1;
   int api_level = atoi(value);
   return (api_level > 0) ? api_level : -1;
diff --git a/libc/include/bits/ioctl.h b/libc/include/bits/ioctl.h
index 9ed1292..fd31a58 100644
--- a/libc/include/bits/ioctl.h
+++ b/libc/include/bits/ioctl.h
@@ -54,11 +54,8 @@
  *   type of the ioctl you prefer, ...), or
  * - defining BIONIC_IOCTL_NO_SIGNEDNESS_OVERLOAD, which will make the
  *   overloading go away.
- *
- * FIXME: __has_extension is more or less a clang version check. Remove it when
- * we don't need to support old clang code.
  */
-#if __has_extension(overloadable_unmarked) && !defined(BIONIC_IOCTL_NO_SIGNEDNESS_OVERLOAD)
+#if !defined(BIONIC_IOCTL_NO_SIGNEDNESS_OVERLOAD)
 /* enable_if(1) just exists to break overloading ties. */
 int ioctl(int __fd, unsigned __request, ...) __overloadable __enable_if(1, "") __RENAME(ioctl);
 #endif
diff --git a/libc/include/signal.h b/libc/include/signal.h
index 9d1030a..c788ca6 100644
--- a/libc/include/signal.h
+++ b/libc/include/signal.h
@@ -114,7 +114,7 @@
 
 int pthread_kill(pthread_t __pthread, int __signal);
 #if defined(__USE_GNU)
-int pthread_sigqueue(pthread_t __pthread, int __signal, const union sigval __value) __INTRODUCED_IN(__ANDROID_API_Q__);
+int pthread_sigqueue(pthread_t __pthread, int __signal, const union sigval __value) __INTRODUCED_IN(29);
 #endif
 
 int pthread_sigmask(int __how, const sigset_t* __new_set, sigset_t* __old_set);
diff --git a/libc/include/sys/cdefs.h b/libc/include/sys/cdefs.h
index 26a05c8..e9d0e4b 100644
--- a/libc/include/sys/cdefs.h
+++ b/libc/include/sys/cdefs.h
@@ -34,36 +34,10 @@
  *	@(#)cdefs.h	8.8 (Berkeley) 1/9/95
  */
 
-#ifndef	_SYS_CDEFS_H_
-#define	_SYS_CDEFS_H_
-
-#include <android/api-level.h>
+#pragma once
 
 #define __BIONIC__ 1
 
-/*
- * Testing against Clang-specific extensions.
- */
-#ifndef __has_extension
-#define __has_extension         __has_feature
-#endif
-#ifndef __has_feature
-#define __has_feature(x)        0
-#endif
-#ifndef __has_include
-#define __has_include(x)        0
-#endif
-#ifndef __has_builtin
-#define __has_builtin(x)        0
-#endif
-#ifndef __has_attribute
-#define __has_attribute(x)      0
-#endif
-
-#define __strong_alias(alias, sym) \
-    __asm__(".global " #alias "\n" \
-            #alias " = " #sym);
-
 #if defined(__cplusplus)
 #define __BEGIN_DECLS extern "C" {
 #define __END_DECLS }
@@ -72,6 +46,10 @@
 #define __END_DECLS
 #endif
 
+#define __strong_alias(alias, sym) \
+    __asm__(".global " #alias "\n" \
+            #alias " = " #sym);
+
 #if defined(__cplusplus)
 #define __BIONIC_CAST(_k,_t,_v) (_k<_t>(_v))
 #else
@@ -88,22 +66,19 @@
  * strings produced by the __STRING macro, but this only works with ANSI C.
  */
 
-#define	___STRING(x)	__STRING(x)
-#define	___CONCAT(x,y)	__CONCAT(x,y)
-
 #define	__P(protos)	protos		/* full-blown ANSI C */
+
 #define	__CONCAT1(x,y)	x ## y
 #define	__CONCAT(x,y)	__CONCAT1(x,y)
+#define	___CONCAT(x,y)	__CONCAT(x,y)
+
 #define	__STRING(x)	#x
+#define	___STRING(x)	__STRING(x)
 
 #if defined(__cplusplus)
 #define	__inline	inline		/* convert to C++ keyword */
 #endif /* !__cplusplus */
 
-#include <android/versioning.h>
-
-#include <android/versioning.h>
-
 #define __always_inline __attribute__((__always_inline__))
 #define __attribute_const__ __attribute__((__const__))
 #define __attribute_pure__ __attribute__((__pure__))
@@ -359,4 +334,5 @@
  */
 #define __unsafe_check_mul_overflow(x, y) ((__SIZE_TYPE__)-1 / (x) < (y))
 
-#endif /* !_SYS_CDEFS_H_ */
+#include <android/versioning.h>
+#include <android/api-level.h>
diff --git a/libc/private/bionic_sdk_version.h b/libc/private/bionic_sdk_version.h
deleted file mode 100644
index b352d9a..0000000
--- a/libc/private/bionic_sdk_version.h
+++ /dev/null
@@ -1,24 +0,0 @@
-/*
- * Copyright (C) 2016 The Android Open Source Project
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-#ifndef _BIONIC_SDK_VERSION_H_
-#define _BIONIC_SDK_VERSION_H_
-
-#include <stdint.h>
-
-int bionic_get_application_target_sdk_version();
-
-#endif  // _BIONIC_SDK_VERSION_H_