Index: include/__config
===================================================================
--- include/__config
+++ include/__config
@@ -167,6 +167,10 @@
 // Need to detect which libc we're using if we're on Linux.
 #if defined(__linux__)
 #include <features.h>
+#if __libcpp_has_include(<sys/cdefs.h>)
+// Needed to detect bionic libc.
+#include <sys/cdefs.h>
+#endif
 #if !defined(__GLIBC_PREREQ)
 #define __GLIBC_PREREQ(a, b) 0
 #endif // !defined(__GLIBC_PREREQ)
@@ -409,7 +413,7 @@
 #define _LIBCPP_HAS_C11_FEATURES
 #elif defined(__linux__)
 #if !defined(_LIBCPP_HAS_MUSL_LIBC)
-#if __GLIBC_PREREQ(2, 15) || defined(__BIONIC__)
+#if __GLIBC_PREREQ(2, 15) || (defined(__BIONIC__) && (__ANDROID_API__ >= 21))
 #define _LIBCPP_HAS_QUICK_EXIT
 #endif
 #if __GLIBC_PREREQ(2, 17)