diff --git a/libcxx/include/__support/android/locale_bionic.h b/libcxx/include/__support/android/locale_bionic.h
--- a/libcxx/include/__support/android/locale_bionic.h
+++ b/libcxx/include/__support/android/locale_bionic.h
@@ -30,6 +30,19 @@
 #if __ANDROID_API__ < 21
 #include <__support/xlocale/__posix_l_fallback.h>
 #endif
+
+// HACK: Not in upstream NDK or libc++.
+// Upstream now supports using ToT libc++ with old NDKs, but as such it is now
+// *only* compatible with the NDK. That will need to be fixed both for the
+// platorm and for the NDK-in-platform use case since neither has
+// android/ndk-version.h.
+
+// If we do not have this header, we are in a platform build rather than an NDK
+// build, which will always be at least as new as the ToT NDK, in which case we
+// don't need any of the inlines below since libc provides them.
+#    if __has_include(<android/ndk-version.h>)
+#      include <android/api-level.h>
+#      include <android/ndk-version.h>
 // In NDK versions later than 16, locale-aware functions are provided by
 // legacy_stdlib_inlines.h
 #if __NDK_MAJOR__ <= 16
@@ -63,6 +76,7 @@
 #endif // __ANDROID_API__ < 26
 
 #endif // __NDK_MAJOR__ <= 16
+#    endif // __has_include(<android/ndk-version.h>)
 #endif // defined(__ANDROID__)
 
 #endif // defined(__BIONIC__)