diff --git a/libc/bionic/swab.cpp b/libc/bionic/swab.cpp
index bc53ba4..59e1c0f 100644
--- a/libc/bionic/swab.cpp
+++ b/libc/bionic/swab.cpp
@@ -28,14 +28,5 @@
 
 #include <unistd.h>
 
-void swab(const void* void_src, void* void_dst, ssize_t byte_count) {
-  const uint8_t* src = static_cast<const uint8_t*>(void_src);
-  uint8_t* dst = static_cast<uint8_t*>(void_dst);
-  while (byte_count > 1) {
-    uint8_t x = *src++;
-    uint8_t y = *src++;
-    *dst++ = y;
-    *dst++ = x;
-    byte_count -= 2;
-  }
-}
+#define __BIONIC_SWAB_INLINE /* Out of line. */
+#include <bits/swab.h>
diff --git a/libc/include/android/legacy_unistd_inlines.h b/libc/include/android/legacy_unistd_inlines.h
new file mode 100644
index 0000000..4a5206b
--- /dev/null
+++ b/libc/include/android/legacy_unistd_inlines.h
@@ -0,0 +1,38 @@
+/*
+ * Copyright (C) 2019 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__ < 28
+
+#define __BIONIC_SWAB_INLINE static __inline
+#include <bits/swab.h>
+
+#endif
diff --git a/libc/include/bits/swab.h b/libc/include/bits/swab.h
new file mode 100644
index 0000000..63281b6
--- /dev/null
+++ b/libc/include/bits/swab.h
@@ -0,0 +1,53 @@
+/*
+ * Copyright (C) 2019 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 <stdint.h>
+#include <sys/cdefs.h>
+#include <sys/types.h>
+
+#if !defined(__BIONIC_SWAB_INLINE)
+#define __BIONIC_SWAB_INLINE static __inline
+#endif
+
+__BEGIN_DECLS
+
+__BIONIC_SWAB_INLINE void swab(const void* __void_src, void* __void_dst, ssize_t __byte_count) {
+  const uint8_t* __src = __BIONIC_CAST(static_cast, const uint8_t*, __void_src);
+  uint8_t* __dst = __BIONIC_CAST(static_cast, uint8_t*, __void_dst);
+  while (__byte_count > 1) {
+    uint8_t x = *__src++;
+    uint8_t y = *__src++;
+    *__dst++ = y;
+    *__dst++ = x;
+    __byte_count -= 2;
+  }
+}
+
+__END_DECLS
diff --git a/libc/include/unistd.h b/libc/include/unistd.h
index aaa8f22..e360421 100644
--- a/libc/include/unistd.h
+++ b/libc/include/unistd.h
@@ -313,7 +313,9 @@
 int getdomainname(char* __buf, size_t __buf_size) __INTRODUCED_IN(26);
 int setdomainname(const char* __name, size_t __n) __INTRODUCED_IN(26);
 
+#if __ANDROID_API__ >= 28
 void swab(const void* __src, void* __dst, ssize_t __byte_count) __INTRODUCED_IN(28);
+#endif
 
 #if defined(__BIONIC_INCLUDE_FORTIFY_HEADERS)
 #define _UNISTD_H_
@@ -322,3 +324,5 @@
 #endif
 
 __END_DECLS
+
+#include <android/legacy_unistd_inlines.h>