What is the default path for OSX system include files when building a C++ application?

I am building a C++ application at the command line (using make with an open-source library (Xerces 2.8)). One of the files includes an OSX system file,

#include <TextUtils.h>

When I type make -n to determine the command used to compile the given file, there is no include path for the system framewor开发者_开发问答k files provided. Therefore, I assume that on OSX the gcc compiler looks in a default location for system include files.

I would like to know what this location is. When I search for TextUtils.h, I see many versions of the file in different locations, including a few different possible candidates for what might be a default location.

How can I determine the default path the system uses for system include files?

Executing the following command

# echo "" | gcc -xc - -v -E

will output the buildin configuration of gcc among which are the default includes.