Index: smart_ptr/detail/sp_counted_base.hpp
===================================================================
--- smart_ptr/detail/sp_counted_base.hpp	(revision 76085)
+++ smart_ptr/detail/sp_counted_base.hpp	(working copy)
@@ -62,6 +62,9 @@
 #elif defined( WIN32 ) || defined( _WIN32 ) || defined( __WIN32__ ) || defined(__CYGWIN__)
 # include <boost/smart_ptr/detail/sp_counted_base_w32.hpp>
 
+#elif defined( _AIX )
+# include <boost/smart_ptr/detail/sp_counted_base_aix.hpp>
+
 #elif !defined( BOOST_HAS_THREADS )
 # include <boost/smart_ptr/detail/sp_counted_base_nt.hpp>
 
Index: smart_ptr/detail/sp_counted_base_aix.hpp
===================================================================
--- smart_ptr/detail/sp_counted_base_aix.hpp	(revision 0)
+++ smart_ptr/detail/sp_counted_base_aix.hpp	(revision 0)
@@ -0,0 +1,113 @@
+#ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_AIX_HPP_INCLUDED
+#define BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_AIX_HPP_INCLUDED
+
+//
+//  detail/sp_counted_base_aix.hpp
+//   based on: detail/sp_counted_base_w32.hpp
+//
+//  Copyright (c) 2001, 2002, 2003 Peter Dimov and Multi Media Ltd.
+//  Copyright 2004-2005 Peter Dimov
+//  Copyright 2006 Michael van der Westhuizen
+//
+//  Distributed under the Boost Software License, Version 1.0. (See
+//  accompanying file LICENSE_1_0.txt or copy at
+//  http://www.boost.org/LICENSE_1_0.txt)
+//
+//
+//  Lock-free algorithm by Alexander Terekhov
+//
+//  Thanks to Ben Hitchings for the #weak + (#shared != 0)
+//  formulation
+//
+
+#include <boost/detail/sp_typeinfo.hpp>
+#include <sys/atomic_op.h>
+
+namespace boost
+{
+
+namespace detail
+{
+
+class sp_counted_base
+{
+private:
+
+    sp_counted_base( sp_counted_base const & );
+    sp_counted_base & operator= ( sp_counted_base const & );
+
+    int32_t use_count_;        // #shared
+    int32_t weak_count_;       // #weak + (#shared != 0)
+
+public:
+
+    sp_counted_base(): use_count_( 1 ), weak_count_( 1 )
+    {
+    }
+
+    virtual ~sp_counted_base() // nothrow
+    {
+    }
+
+    // dispose() is called when use_count_ drops to zero, to release
+    // the resources managed by *this.
+
+    virtual void dispose() = 0; // nothrow
+
+    // destroy() is called when weak_count_ drops to zero.
+
+    virtual void destroy() // nothrow
+    {
+        delete this;
+    }
+
+    virtual void * get_deleter( sp_typeinfo const & ti ) = 0;
+
+    void add_ref_copy()
+    {
+        fetch_and_add( &use_count_, 1 );
+    }
+
+    bool add_ref_lock() // true on success
+    {
+        int32_t tmp = fetch_and_add( &use_count_, 0 );
+        for( ;; )
+        {
+            if( tmp == 0 ) return false;
+            if( compare_and_swap( &use_count_, &tmp, tmp + 1 ) ) return true;
+        }
+    }
+
+    void release() // nothrow
+    {
+        if( fetch_and_add( &use_count_, -1 ) == 1 )
+        {
+            dispose();
+            weak_release();
+        }
+    }
+
+    void weak_add_ref() // nothrow
+    {
+        fetch_and_add( &weak_count_, 1 );
+    }
+
+    void weak_release() // nothrow
+    {
+        if( fetch_and_add( &weak_count_, -1 ) == 1 )
+        {
+            destroy();
+        }
+    }
+
+    long use_count() const // nothrow
+    {
+        return fetch_and_add( const_cast<int32_t*>(&use_count_), 0 );
+    }
+};
+
+} // namespace detail
+
+} // namespace boost
+
+#endif  // #ifndef BOOST_SMART_PTR_DETAIL_SP_COUNTED_BASE_AIX_HPP_INCLUDED