diff --git a/libcxx/test/std/localization/locale.categories/category.numeric/locale.nm.put/facet.num.put.members/put_long_double.pass.cpp b/libcxx/test/std/localization/locale.categories/category.numeric/locale.nm.put/facet.num.put.members/put_long_double.pass.cpp
--- a/libcxx/test/std/localization/locale.categories/category.numeric/locale.nm.put/facet.num.put.members/put_long_double.pass.cpp
+++ b/libcxx/test/std/localization/locale.categories/category.numeric/locale.nm.put/facet.num.put.members/put_long_double.pass.cpp
@@ -10732,7 +10732,8 @@
     std::string nan= "nan";
     std::string NaN = "NAN";
     std::string nan_padding25 = "**********************";
-#if defined(TEST_HAS_GLIBC) || defined(_WIN32)
+#if defined(TEST_HAS_GLIBC) || defined(_WIN32) || \
+        (defined(__BIONIC__) && !defined(_LIBCPP_TESTING_ANDROID_PRINTF_NAN_NO_SIGN))
     std::string pnan_sign = "+";
     std::string pnan_padding25 = "*********************";
 #else
diff --git a/libcxx/utils/libcxx/test/features.py b/libcxx/utils/libcxx/test/features.py
--- a/libcxx/utils/libcxx/test/features.py
+++ b/libcxx/utils/libcxx/test/features.py
@@ -142,6 +142,24 @@
             }
           """)),
 
+  # Check for an Android NAN printf change. Considering NAN and -NAN:
+  #  - Android L (API 21): "%f" and "%+f" print "nan".
+  #  - Android M (API 23) and up: "%f" prints "nan" or "-nan", "%+f" prints
+  #    "+nan" or "-nan".
+  # Set this feature for L, where the sign is never printed. Otherwise, "%+f"
+  # for non-negative NAN prints the '+' sign.
+  Feature(name='android-printf-nan-no-sign',
+          when=lambda cfg: '__ANDROID__' in compilerMacros(cfg) and not programSucceeds(cfg, """
+            #include <math.h>
+            #include <stdio.h>
+            int main(int, char**) {
+              char buf[100];
+              snprintf(buf, sizeof(buf), "%+f", NAN);
+              return buf[0] != '+';
+            }
+          """),
+          actions=[AddCompileFlag('-D_LIBCPP_TESTING_ANDROID_PRINTF_NAN_NO_SIGN')]),
+
   # Whether Bash can run on the executor.
   # This is not always the case, for example when running on embedded systems.
   #