diff --git a/libcxx/include/clocale b/libcxx/include/clocale
--- a/libcxx/include/clocale
+++ b/libcxx/include/clocale
@@ -47,7 +47,9 @@
 #ifndef _LIBCPP_HAS_NO_THREAD_UNSAFE_C_FUNCTIONS
 using ::setlocale;
 #endif
+#if !defined(__ANDROID__) || (__ANDROID_API__ >= 21)
 using ::localeconv;
+#endif
 
 _LIBCPP_END_NAMESPACE_STD
 
diff --git a/libcxx/include/cmath b/libcxx/include/cmath
--- a/libcxx/include/cmath
+++ b/libcxx/include/cmath
@@ -450,7 +450,9 @@
 using ::nearbyintf;
 using ::nextafter;
 using ::nextafterf;
+#if !defined(__ANDROID__) || (__ANDROID_API__ >= 18)
 using ::nexttoward;
+#endif
 using ::nexttowardf;
 using ::remainder;
 using ::remainderf;
@@ -460,8 +462,10 @@
 using ::rintf;
 using ::round;
 using ::roundf;
+#if !defined(__ANDROID__) || (__ANDROID_API__ >= 18)
 using ::scalbln;
 using ::scalblnf;
+#endif
 using ::scalbn;
 using ::scalbnf;
 using ::tgamma;
@@ -519,13 +523,19 @@
 using ::lroundl;
 using ::nanl;
 using ::nearbyintl;
+#if !defined(__ANDROID__) || (__ANDROID_API__ >= 21)
 using ::nextafterl;
+#endif
+#if !defined(__ANDROID__) || (__ANDROID_API__ >= 18)
 using ::nexttowardl;
+#endif
 using ::remainderl;
 using ::remquol;
 using ::rintl;
 using ::roundl;
+#if !defined(__ANDROID__) || (__ANDROID_API__ >= 18)
 using ::scalblnl;
+#endif
 using ::scalbnl;
 using ::tgammal;
 using ::truncl;
diff --git a/libcxx/include/cstdlib b/libcxx/include/cstdlib
--- a/libcxx/include/cstdlib
+++ b/libcxx/include/cstdlib
@@ -145,9 +145,13 @@
 #ifndef _LIBCPP_HAS_NO_LONG_LONG
 using ::lldiv;
 #endif // _LIBCPP_HAS_NO_LONG_LONG
+#if !defined(__ANDROID__) || (__ANDROID_API__ >= 26)
 using ::mblen;
+#endif
+#if !defined(__ANDROID__) || (__ANDROID_API__ >= 21)
 using ::mbtowc;
 using ::wctomb;
+#endif
 using ::mbstowcs;
 using ::wcstombs;
 #if !defined(_LIBCPP_CXX03_LANG) && defined(_LIBCPP_HAS_QUICK_EXIT)
diff --git a/libcxx/include/cwctype b/libcxx/include/cwctype
--- a/libcxx/include/cwctype
+++ b/libcxx/include/cwctype
@@ -78,8 +78,10 @@
 using ::wctype;
 using ::towlower;
 using ::towupper;
+#if !defined(__ANDROID__) || (__ANDROID_API__ >= 26)
 using ::towctrans;
 using ::wctrans;
+#endif
 
 _LIBCPP_END_NAMESPACE_STD
 
diff --git a/libcxx/include/math.h b/libcxx/include/math.h
--- a/libcxx/include/math.h
+++ b/libcxx/include/math.h
@@ -1396,6 +1396,7 @@
 
 // nexttoward
 
+#if !defined(__ANDROID__) || (__ANDROID_API__ >= 18)
 inline _LIBCPP_INLINE_VISIBILITY float       nexttoward(float __lcpp_x, long double __lcpp_y) _NOEXCEPT       {return ::nexttowardf(__lcpp_x, __lcpp_y);}
 inline _LIBCPP_INLINE_VISIBILITY long double nexttoward(long double __lcpp_x, long double __lcpp_y) _NOEXCEPT {return ::nexttowardl(__lcpp_x, __lcpp_y);}
 
@@ -1403,6 +1404,7 @@
 inline _LIBCPP_INLINE_VISIBILITY
 typename std::enable_if<std::is_integral<_A1>::value, double>::type
 nexttoward(_A1 __lcpp_x, long double __lcpp_y) _NOEXCEPT {return ::nexttoward((double)__lcpp_x, __lcpp_y);}
+#endif
 
 // remainder
 
@@ -1468,6 +1470,7 @@
 
 // scalbln
 
+#if !defined(__ANDROID__) || (__ANDROID_API__ >= 18)
 inline _LIBCPP_INLINE_VISIBILITY float       scalbln(float __lcpp_x, long __lcpp_y) _NOEXCEPT       {return ::scalblnf(__lcpp_x, __lcpp_y);}
 inline _LIBCPP_INLINE_VISIBILITY long double scalbln(long double __lcpp_x, long __lcpp_y) _NOEXCEPT {return ::scalblnl(__lcpp_x, __lcpp_y);}
 
@@ -1475,6 +1478,7 @@
 inline _LIBCPP_INLINE_VISIBILITY
 typename std::enable_if<std::is_integral<_A1>::value, double>::type
 scalbln(_A1 __lcpp_x, long __lcpp_y) _NOEXCEPT {return ::scalbln((double)__lcpp_x, __lcpp_y);}
+#endif
 
 // scalbn