diff --git a/include/boost/function.hpp b/include/boost/function.hpp
index ef907e0..3039a0e 100644
--- a/include/boost/function.hpp
+++ b/include/boost/function.hpp
@@ -10,6 +10,364 @@
 // William Kempf, Jesse Jones and Karl Nelson were all very helpful in the
 // design of this library.
 
+#include <boost/function/detail/config.hpp>
+
+#if !BOOST_FUNCTION_ENABLE_CXX03
+
+#ifndef BOOST_FUNCTION_HPP_INCLUDED
+#define BOOST_FUNCTION_HPP_INCLUDED
+
+#include <boost/ref.hpp>
+#include <boost/function_equal.hpp>
+#include <functional>
+#include <type_traits>
+
+namespace boost
+{
+
+#define BOOST_FUNCTION_TARGET_FIX(x)
+
+using std::bad_function_call;
+
+template<class S> class function: public std::function<S>
+{
+public:
+
+    function() = default;
+
+    function(function const&) = default;
+    function(function&&) = default;
+
+    using std::function<S>::function;
+
+    template<class T> function( boost::reference_wrapper<T> rt ): std::function<S>( std::ref( rt.get() ) )
+    {
+    }
+
+    function& operator=( function const& r ) = default;
+    function& operator=( function&& r ) = default;
+
+    template<class S2> function& operator=( function<S2> const& r )
+    {
+        std::function<S>::operator=( static_cast< std::function<S2> const& >( r ) );
+        return *this;
+    }
+
+    template<class S2> function& operator=( function<S2>&& r )
+    {
+        std::function<S>::operator=( static_cast< std::function<S2>&& >( r ) );
+        return *this;
+    }
+
+    template<class F, class E = typename std::enable_if< !std::is_integral<F>::value && !std::is_same<F, function>::value >::type > function& operator=( F f )
+    {
+        std::function<S>::operator=( std::move( f ) );
+        return *this;
+    }
+
+    function& operator=( std::nullptr_t f )
+    {
+        std::function<S>::operator=( f );
+        return *this;
+    }
+
+    template<class T> function& operator=( boost::reference_wrapper<T> rt )
+    {
+        std::function<S>::operator=( std::ref( rt.get() ) );
+        return *this;
+    }
+
+    bool empty() const noexcept
+    {
+        return ! *this;
+    }
+
+    void clear()
+    {
+        *this = nullptr;
+    }
+
+    template<class F, class A> void assign( F f, A )
+    {
+        this->operator=( std::move( f ) );
+    }
+
+    template<class F> F * target() noexcept
+    {
+        if( F * p = std::function<S>::template target<F>() )
+        {
+            return p;
+        }
+
+        if( std::reference_wrapper<F> * p = std::function<S>::template target< std::reference_wrapper<F> >() )
+        {
+            return std::addressof( p->get() );
+        }
+
+        return nullptr;
+    }
+
+    template<class F> F const * target() const noexcept
+    {
+        if( F const * p = std::function<S>::template target<F>() )
+        {
+            return p;
+        }
+
+        if( std::reference_wrapper<F> const * p = std::function<S>::template target< std::reference_wrapper<F> >() )
+        {
+            return std::addressof( p->get() );
+        }
+
+        return nullptr;
+    }
+
+    template<class F> bool contains( F const& f ) const noexcept
+    {
+        if( F const * fp = this->template target<F>() )
+        {
+            return function_equal( *fp, f );
+        }
+        else
+        {
+            return false;
+        }
+    }
+};
+
+template<class S, class F, class E = typename std::enable_if< !std::is_integral<F>::value && !std::is_same<F, std::nullptr_t>::value>::type> inline bool operator==( function<S> const & g, F f )
+{
+    return g.contains( f );
+}
+
+template<class S, class F, class E = typename std::enable_if< !std::is_integral<F>::value && !std::is_same<F, std::nullptr_t>::value>::type> inline bool operator!=( function<S> const & g, F f )
+{
+    return !g.contains( f );
+}
+
+template<class S, class F> inline bool operator==( function<S> const & g, boost::reference_wrapper<F> rf )
+{
+    return g.template target<F>() == std::addressof( rf.get() );
+}
+
+template<class S, class F> inline bool operator!=( function<S> const & g, boost::reference_wrapper<F> rf )
+{
+    return g.template target<F>() != std::addressof( rf.get() );
+}
+
+template<class S, class F, class E = typename std::enable_if< !std::is_integral<F>::value && !std::is_same<F, std::nullptr_t>::value>::type> inline bool operator==( F f, function<S> const & g )
+{
+    return g.contains( f );
+}
+
+template<class S, class F, class E = typename std::enable_if< !std::is_integral<F>::value && !std::is_same<F, std::nullptr_t>::value>::type> inline bool operator!=( F f, function<S> const & g )
+{
+    return !g.contains( f );
+}
+
+template<class S, class F> inline bool operator==( boost::reference_wrapper<F> rf, function<S> const & g )
+{
+    return g.template target<F>() == std::addressof( rf.get() );
+}
+
+template<class S, class F> inline bool operator!=( boost::reference_wrapper<F> rf, function<S> const & g )
+{
+    return g.template target<F>() != std::addressof( rf.get() );
+}
+
+namespace detail
+{
+
+template<class T1, class T2> struct is_similar
+{
+    BOOST_STATIC_CONSTANT( bool, value = false );
+};
+
+template<template<class...> class L, class... T1, class... T2> struct is_similar< L<T1...>, L<T2...> >
+{
+    BOOST_STATIC_CONSTANT( bool, value = true );
+};
+
+} // namespace detail
+
+#define BOOST_FUNCTION_N_COMMON \
+\
+    using base_type::base_type;\
+\
+    template<class F, class E = typename std::enable_if< !std::is_integral<F>::value && !detail::is_similar<F, this_type>::value >::type > this_type& operator=( F f )\
+    {\
+        base_type::operator=( std::move( f ) );\
+        return *this;\
+    }\
+\
+    this_type& operator=( std::nullptr_t f )\
+    {\
+        base_type::operator=( f );\
+        return *this;\
+    }\
+\
+    template<class S2> this_type& operator=( boost::function<S2> const& r )\
+    {\
+        base_type::operator=( r );\
+        return *this;\
+    }\
+\
+    template<class S2> this_type& operator=( boost::function<S2>&& r )\
+    {\
+        base_type::operator=( std::move( r ) );\
+        return *this;\
+    }
+
+template<typename R> class function0: public function<R()>
+{
+private:
+
+    typedef function0 this_type;
+    typedef function<R()> base_type;
+
+public:
+
+	BOOST_FUNCTION_N_COMMON
+};
+
+template<typename R, typename T1> class function1: public function<R(T1)>
+{
+private:
+
+    typedef function1 this_type;
+    typedef function<R(T1)> base_type;
+
+public:
+
+	BOOST_FUNCTION_N_COMMON
+};
+
+template<typename R, typename T1, typename T2> class function2: public function<R(T1, T2)>
+{
+private:
+
+    typedef function2 this_type;
+    typedef function<R(T1, T2)> base_type;
+
+public:
+
+	BOOST_FUNCTION_N_COMMON
+};
+
+template<typename R, typename T1, typename T2, typename T3> class function3: public function<R(T1, T2, T3)>
+{
+private:
+
+    typedef function3 this_type;
+    typedef function<R(T1, T2, T3)> base_type;
+
+public:
+
+	BOOST_FUNCTION_N_COMMON
+};
+
+template<typename R, typename T1, typename T2, typename T3, typename T4> class function4: public function<R(T1, T2, T3, T4)>
+{
+private:
+
+    typedef function4 this_type;
+    typedef function<R(T1, T2, T3, T4)> base_type;
+
+public:
+
+	BOOST_FUNCTION_N_COMMON
+};
+
+template<typename R, typename T1, typename T2, typename T3, typename T4, typename T5> class function5: public function<R(T1, T2, T3, T4, T5)>
+{
+private:
+
+    typedef function5 this_type;
+    typedef function<R(T1, T2, T3, T4, T5)> base_type;
+
+public:
+
+	BOOST_FUNCTION_N_COMMON
+};
+
+template<typename R, typename T1, typename T2, typename T3, typename T4, typename T5, typename T6> class function6: public function<R(T1, T2, T3, T4, T5, T6)>
+{
+private:
+
+    typedef function6 this_type;
+    typedef function<R(T1, T2, T3, T4, T5, T6)> base_type;
+
+public:
+
+	BOOST_FUNCTION_N_COMMON
+};
+
+template<typename R, typename T1, typename T2, typename T3, typename T4, typename T5, typename T6, typename T7> class function7: public function<R(T1, T2, T3, T4, T5, T6, T7)>
+{
+private:
+
+    typedef function7 this_type;
+    typedef function<R(T1, T2, T3, T4, T5, T6, T7)> base_type;
+
+public:
+
+	BOOST_FUNCTION_N_COMMON
+};
+
+template<typename R, typename T1, typename T2, typename T3, typename T4, typename T5, typename T6, typename T7, typename T8> class function8: public function<R(T1, T2, T3, T4, T5, T6, T7, T8)>
+{
+private:
+
+    typedef function8 this_type;
+    typedef function<R(T1, T2, T3, T4, T5, T6, T7, T8)> base_type;
+
+public:
+
+	BOOST_FUNCTION_N_COMMON
+};
+
+template<typename R, typename T1, typename T2, typename T3, typename T4, typename T5, typename T6, typename T7, typename T8, typename T9> class function9: public function<R(T1, T2, T3, T4, T5, T6, T7, T8, T9)>
+{
+private:
+
+    typedef function9 this_type;
+    typedef function<R(T1, T2, T3, T4, T5, T6, T7, T8, T9)> base_type;
+
+public:
+
+	BOOST_FUNCTION_N_COMMON
+};
+
+template<typename R, typename T1, typename T2, typename T3, typename T4, typename T5, typename T6, typename T7, typename T8, typename T9, typename T10> class function10: public function<R(T1, T2, T3, T4, T5, T6, T7, T8, T9, T10)>
+{
+private:
+
+    typedef function10 this_type;
+    typedef function<R(T1, T2, T3, T4, T5, T6, T7, T8, T9, T10)> base_type;
+
+public:
+
+	BOOST_FUNCTION_N_COMMON
+};
+
+template<typename R, typename... A> class function30: public function<R(A...)>
+{
+private:
+
+    typedef function30 this_type;
+    typedef function<R(A...)> base_type;
+
+public:
+
+	BOOST_FUNCTION_N_COMMON
+};
+
+} // namespace boost
+
+#endif // #ifndef BOOST_FUNCTION_HPP_INCLUDED
+
+#else
+
 #ifndef BOOST_FUNCTION_MAX_ARGS
 #  define BOOST_FUNCTION_MAX_ARGS 10
 #endif // BOOST_FUNCTION_MAX_ARGS
@@ -72,3 +430,5 @@
 #endif
 
 #endif // !defined(BOOST_FUNCTION_MAX_ARGS_DEFINED) || (BOOST_FUNCTION_MAX_ARGS_DEFINED != BOOST_FUNCTION_MAX_ARGS)
+
+#endif
diff --git a/include/boost/function/detail/config.hpp b/include/boost/function/detail/config.hpp
new file mode 100644
index 0000000..0c91df8
--- /dev/null
+++ b/include/boost/function/detail/config.hpp
@@ -0,0 +1,12 @@
+// Copyright 2019 Peter Dimov
+// Use, modification and distribution is subject to 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
+
+#ifndef BOOST_FUNCTION_DETAIL_CONFIG_HPP_INCLUDED
+#define BOOST_FUNCTION_DETAIL_CONFIG_HPP_INCLUDED
+
+#if !defined(BOOST_FUNCTION_ENABLE_CXX03)
+# define BOOST_FUNCTION_ENABLE_CXX03 0
+#endif
+
+#endif // #ifndef BOOST_FUNCTION_DETAIL_CONFIG_HPP_INCLUDED
diff --git a/include/boost/function/detail/maybe_include.hpp b/include/boost/function/detail/maybe_include.hpp
index ec88905..878ce46 100644
--- a/include/boost/function/detail/maybe_include.hpp
+++ b/include/boost/function/detail/maybe_include.hpp
@@ -7,6 +7,10 @@
 
 // For more information, see http://www.boost.org
 
+#include <boost/function/detail/config.hpp>
+
+#if BOOST_FUNCTION_ENABLE_CXX03
+
 #if BOOST_FUNCTION_NUM_ARGS == 0
 #  undef BOOST_FUNCTION_MAX_ARGS_DEFINED
 #  define BOOST_FUNCTION_MAX_ARGS_DEFINED 0
@@ -367,3 +371,5 @@
 #else
 #  error Cannot handle Boost.Function objects that accept more than 50 arguments!
 #endif
+
+#endif
diff --git a/include/boost/function/function_fwd.hpp b/include/boost/function/function_fwd.hpp
index e79b504..f36cedd 100644
--- a/include/boost/function/function_fwd.hpp
+++ b/include/boost/function/function_fwd.hpp
@@ -9,6 +9,7 @@
 #ifndef BOOST_FUNCTION_FWD_HPP
 #define BOOST_FUNCTION_FWD_HPP
 #include <boost/config.hpp>
+#include <boost/function/detail/config.hpp>
 
 #if defined(__sgi) && defined(_COMPILER_VERSION) && _COMPILER_VERSION <= 730 && !defined(BOOST_STRICT_CONFIG)
 // Work around a compiler bug.
@@ -24,9 +25,22 @@ namespace boost { namespace python { namespace objects {
 #  define BOOST_FUNCTION_NO_FUNCTION_TYPE_SYNTAX
 #endif
 
+#if !BOOST_FUNCTION_ENABLE_CXX03
+# include <functional>
+#endif
+
 namespace boost {
+
+#if BOOST_FUNCTION_ENABLE_CXX03
+
   class bad_function_call;
 
+#else
+
+  using std::bad_function_call;
+
+#endif
+
 #if !defined(BOOST_FUNCTION_NO_FUNCTION_TYPE_SYNTAX)
   // Preferred syntax
   template<typename Signature> class function;