diff --git a/libc/include/android/legacy_strings_inlines.h b/libc/include/android/legacy_strings_inlines.h
new file mode 100644
index 0000000..6679c30
--- /dev/null
+++ b/libc/include/android/legacy_strings_inlines.h
@@ -0,0 +1,44 @@
+/*
+ * Copyright (C) 2017 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.
+ */
+
+#ifndef _ANDROID_LEGACY_STRINGS_INLINES_H_
+#define _ANDROID_LEGACY_STRINGS_INLINES_H_
+
+#include <strings.h>
+#include <sys/cdefs.h>
+
+__BEGIN_DECLS
+
+#if defined(__i386__) && __ANDROID_API__ < __ANDROID_API_J_MR2__
+/* Everyone except x86 had ffs since the beginning. */
+static __inline int ffs(int __n) { return __builtin_ffs(__n); }
+#endif
+
+__END_DECLS
+
+#endif
diff --git a/libc/include/strings.h b/libc/include/strings.h
index 021e2b4..11f3213 100644
--- a/libc/include/strings.h
+++ b/libc/include/strings.h
@@ -54,8 +54,12 @@
 #define bzero(b, len) (void)(__builtin_memset((b), '\0', (len)))
 #endif
 
+#if !defined(__i386__) || __ANDROID_API__ >= __ANDROID_API_J_MR2__
 int ffs(int) __INTRODUCED_IN_X86(18);
+#endif
 
 __END_DECLS
 
+#include <android/legacy_strings_inlines.h>
+
 #endif /* !defined(_STRINGS_H_) */