diff --git a/core/binary.mk b/core/binary.mk
index ce81762..86dccac 100644
--- a/core/binary.mk
+++ b/core/binary.mk
@@ -166,67 +166,7 @@
 
 my_cflags := $(filter-out $($(LOCAL_2ND_ARCH_VAR_PREFIX)$(my_prefix)GLOBAL_UNSUPPORTED_CFLAGS),$(my_cflags))
 
-# Only around for development purposes. Will be removed soon.
-my_libcxx_is_default := false
-
-# Select the appropriate C++ STL
-ifeq ($(strip $(LOCAL_CXX_STL)),default)
-    ifndef LOCAL_SDK_VERSION
-        ifeq ($(strip $(my_libcxx_is_default)),true)
-            # Platform code. Select the appropriate STL.
-            my_cxx_stl := libc++
-        else
-            my_cxx_stl := bionic
-        endif
-    else
-        my_cxx_stl := ndk
-    endif
-else
-    my_cxx_stl := $(strip $(LOCAL_CXX_STL))
-endif
-
-ifneq ($(filter $(my_cxx_stl),libc++ libc++_static),)
-    my_cflags += -D_USING_LIBCXX
-    my_c_includes += external/libcxx/include
-    ifeq ($(my_cxx_stl),libc++)
-        my_shared_libraries += libc++
-    else
-        my_static_libraries += libc++_static
-    endif
-
-    ifdef LOCAL_IS_HOST_MODULE
-        my_cppflags += -nostdinc++
-        my_ldflags += -nodefaultlibs
-        my_ldlibs += -lc -lm
-    endif
-else ifneq ($(filter $(my_cxx_stl),stlport stlport_static),)
-    my_c_includes += external/stlport/stlport bionic/libstdc++/include bionic
-    ifeq ($(my_cxx_stl),stlport)
-        my_shared_libraries += libstdc++ libstlport
-    else
-        my_static_libraries += libstdc++ libstlport_static
-    endif
-else ifeq ($(my_cxx_stl),ndk)
-    # Using an NDK STL. Handled farther up in this file.
-    ifndef LOCAL_IS_HOST_MODULE
-        my_system_shared_libraries += libstdc++
-    endif
-else ifeq ($(my_cxx_stl),bionic)
-    # Using bionic's basic libstdc++. Not actually an STL. Only around until the
-    # tree is in good enough shape to not need it.
-    ifndef LOCAL_IS_HOST_MODULE
-        my_c_includes += bionic/libstdc++/include
-        my_system_shared_libraries += libstdc++
-    endif
-    # Host builds will use GNU libstdc++.
-else ifeq ($(my_cxx_stl),none)
-    ifdef LOCAL_IS_HOST_MODULE
-        my_cppflags += -nostdinc++
-        my_ldflags += -nodefaultlibs -lc -lm
-    endif
-else
-    $(error $(my_cxx_stl) is not a supported STL.)
-endif
+include $(BUILD_SYSTEM)/cxx_stl_setup.mk
 
 # Add static HAL libraries
 ifdef LOCAL_HAL_STATIC_LIBRARIES
diff --git a/core/cxx_stl_setup.mk b/core/cxx_stl_setup.mk
new file mode 100644
index 0000000..5abdf70
--- /dev/null
+++ b/core/cxx_stl_setup.mk
@@ -0,0 +1,67 @@
+#############################################################
+## Set up flags based on LOCAL_CXX_STL.
+## Input variables: LOCAL_CXX_STL
+## Output variables: My_cflags, my_c_includes, my_shared_libraries, etc.
+#############################################################
+
+# Only around for development purposes. Will be removed soon.
+my_libcxx_is_default := false
+
+# Select the appropriate C++ STL
+ifeq ($(strip $(LOCAL_CXX_STL)),default)
+    ifndef LOCAL_SDK_VERSION
+        ifeq ($(strip $(my_libcxx_is_default)),true)
+            # Platform code. Select the appropriate STL.
+            my_cxx_stl := libc++
+        else
+            my_cxx_stl := bionic
+        endif
+    else
+        my_cxx_stl := ndk
+    endif
+else
+    my_cxx_stl := $(strip $(LOCAL_CXX_STL))
+endif
+
+ifneq ($(filter $(my_cxx_stl),libc++ libc++_static),)
+    my_cflags += -D_USING_LIBCXX
+    my_c_includes += external/libcxx/include
+    ifeq ($(my_cxx_stl),libc++)
+        my_shared_libraries += libc++
+    else
+        my_static_libraries += libc++_static
+    endif
+
+    ifdef LOCAL_IS_HOST_MODULE
+        my_cppflags += -nostdinc++
+        my_ldflags += -nodefaultlibs
+        my_ldlibs += -lc -lm
+    endif
+else ifneq ($(filter $(my_cxx_stl),stlport stlport_static),)
+    my_c_includes += external/stlport/stlport bionic/libstdc++/include bionic
+    ifeq ($(my_cxx_stl),stlport)
+        my_shared_libraries += libstdc++ libstlport
+    else
+        my_static_libraries += libstdc++ libstlport_static
+    endif
+else ifeq ($(my_cxx_stl),ndk)
+    # Using an NDK STL. Handled farther up in this file.
+    ifndef LOCAL_IS_HOST_MODULE
+        my_system_shared_libraries += libstdc++
+    endif
+else ifeq ($(my_cxx_stl),bionic)
+    # Using bionic's basic libstdc++. Not actually an STL. Only around until the
+    # tree is in good enough shape to not need it.
+    ifndef LOCAL_IS_HOST_MODULE
+        my_c_includes += bionic/libstdc++/include
+        my_system_shared_libraries += libstdc++
+    endif
+    # Host builds will use GNU libstdc++.
+else ifeq ($(my_cxx_stl),none)
+    ifdef LOCAL_IS_HOST_MODULE
+        my_cppflags += -nostdinc++
+        my_ldflags += -nodefaultlibs -lc -lm
+    endif
+else
+    $(error $(my_cxx_stl) is not a supported STL.)
+endif
diff --git a/core/prebuilt_internal.mk b/core/prebuilt_internal.mk
index 551cf2d..69f2986 100644
--- a/core/prebuilt_internal.mk
+++ b/core/prebuilt_internal.mk
@@ -101,20 +101,23 @@
 # of the shared libraries are determined.
 ifdef LOCAL_INSTALLED_MODULE
 ifdef LOCAL_SHARED_LIBRARIES
+my_shared_libraries := $(LOCAL_SHARED_LIBRARIES)
+# Extra shared libraries introduced by LOCAL_CXX_STL.
+include $(BUILD_SYSTEM)/cxx_stl_setup.mk
 $(LOCAL_2ND_ARCH_VAR_PREFIX)$(my_prefix)DEPENDENCIES_ON_SHARED_LIBRARIES += \
-  $(my_register_name):$(LOCAL_INSTALLED_MODULE):$(subst $(space),$(comma),$(LOCAL_SHARED_LIBRARIES))
+  $(my_register_name):$(LOCAL_INSTALLED_MODULE):$(subst $(space),$(comma),$(my_shared_libraries))
 
 # We also need the LOCAL_BUILT_MODULE dependency,
 # since we use -rpath-link which points to the built module's path.
-built_shared_libraries := \
+my_built_shared_libraries := \
     $(addprefix $($(LOCAL_2ND_ARCH_VAR_PREFIX)$(my_prefix)OUT_INTERMEDIATE_LIBRARIES)/, \
     $(addsuffix $($(my_prefix)SHLIB_SUFFIX), \
-        $(LOCAL_SHARED_LIBRARIES)))
-$(LOCAL_BUILT_MODULE) : $(built_shared_libraries)
+        $(my_shared_libraries)))
+$(LOCAL_BUILT_MODULE) : $(my_built_shared_libraries)
 endif
 endif
 
-# We need to enclose the above export_includes and built_shared_libraries in
+# We need to enclose the above export_includes and my_built_shared_libraries in
 # "LOCAL_STRIP_MODULE not true" because otherwise the rules are defined in dynamic_binary.mk.
 endif  # LOCAL_STRIP_MODULE not true