--- a/build/autoconf/android.m4
+++ b/build/autoconf/android.m4
@@ -90,17 +90,19 @@ if test "$OS_TARGET" = "Android"; then
 fi
 ])
 
 AC_DEFUN([MOZ_ANDROID_STLPORT],
 [
 
 if test "$OS_TARGET" = "Android"; then
     cpu_arch_dir="$ANDROID_CPU_ARCH"
-    if test "$MOZ_THUMB2" = 1; then
+    # NDK r12 removed the arm/thumb library split and just made everything
+    # thumb by default.  Attempt to compensate.
+    if test "$MOZ_THUMB2" = 1 -a -d "$cpu_arch_dir/thumb"; then
         cpu_arch_dir="$cpu_arch_dir/thumb"
     fi
 
     if test -z "$STLPORT_CPPFLAGS$STLPORT_LIBS"; then
         case "$android_cxx_stl" in
         libstdc++)
             # android-ndk-r8b and later
             ndk_base="$android_ndk/sources/cxx-stl/gnu-libstdc++/$android_gnu_compiler_version"
@@ -124,16 +126,22 @@ if test "$OS_TARGET" = "Android"; then
             cxxabi_base="$ndk_base/llvm-libc++abi"
             cxxabi_include="$cxxabi_base/libcxxabi/include"
 
             if ! test -e "$cxx_libs/libc++_static.a"; then
                 AC_MSG_ERROR([Couldn't find path to llvm-libc++ in the android ndk])
             fi
 
             STLPORT_LIBS="-L$cxx_libs -lc++_static"
+            # NDK r12 split the libc++ runtime libraries into pieces.
+            for lib in c++abi unwind android_support; do
+                if test -e "$cxx_libs/lib${lib}.a"; then
+                     STLPORT_LIBS="$STLPORT_LIBS -l${lib}"
+                fi
+            done
             # Add android/support/include/ for prototyping long double math
             # functions, locale-specific C library functions, multibyte support,
             # etc.
             STLPORT_CPPFLAGS="-I$android_ndk/sources/android/support/include -I$cxx_include -I$cxxabi_include"
             ;;
         mozstlport)
             # We don't need to set STLPORT_LIBS, because the build system will
             # take care of linking in our home-built stlport where it is needed.