Index: include/__config
===================================================================
--- include/__config
+++ include/__config
@@ -719,4 +719,12 @@
          _LIBCPP_HAS_NO_THREADS is defined.
 #endif
 
+// Systems that use capability-based security (FreeBSD with Capsicum,
+// Nuxi CloudABI) may only provide local filesystem access (using *at()).
+// Functions like open(), rename(), unlink() and stat() should not be
+// used, as they attempt to access the global filesystem namespace.
+#ifndef __CloudABI__
+#define _LIBCPP_HAS_GLOBAL_FILESYSTEM_NAMESPACE
+#endif
+
 #endif  // _LIBCPP_CONFIG
Index: include/cstdio
===================================================================
--- include/cstdio
+++ include/cstdio
@@ -144,14 +144,18 @@
 using ::fpos_t;
 using ::size_t;
 
+#ifdef _LIBCPP_HAS_GLOBAL_FILESYSTEM_NAMESPACE
 using ::remove;
 using ::rename;
 using ::tmpfile;
 using ::tmpnam;
+#endif
 using ::fclose;
 using ::fflush;
+#ifdef _LIBCPP_HAS_GLOBAL_FILESYSTEM_NAMESPACE
 using ::fopen;
 using ::freopen;
+#endif
 using ::setbuf;
 using ::setvbuf;
 using ::fprintf;
Index: include/fstream
===================================================================
--- include/fstream
+++ include/fstream
@@ -206,8 +206,10 @@
 
     // 27.9.1.4 Members:
     bool is_open() const;
+#ifdef _LIBCPP_HAS_GLOBAL_FILESYSTEM_NAMESPACE
     basic_filebuf* open(const char* __s, ios_base::openmode __mode);
     basic_filebuf* open(const string& __s, ios_base::openmode __mode);
+#endif
     basic_filebuf* close();
 
 protected:
@@ -463,6 +465,7 @@
     return __file_ != 0;
 }
 
+#ifdef _LIBCPP_HAS_GLOBAL_FILESYSTEM_NAMESPACE
 template <class _CharT, class _Traits>
 basic_filebuf<_CharT, _Traits>*
 basic_filebuf<_CharT, _Traits>::open(const char* __s, ios_base::openmode __mode)
@@ -550,6 +553,7 @@
 {
     return open(__s.c_str(), __mode);
 }
+#endif
 
 template <class _CharT, class _Traits>
 basic_filebuf<_CharT, _Traits>*
@@ -1005,8 +1009,10 @@
     typedef typename traits_type::off_type off_type;
 
     basic_ifstream();
+#ifdef _LIBCPP_HAS_GLOBAL_FILESYSTEM_NAMESPACE
     explicit basic_ifstream(const char* __s, ios_base::openmode __mode = ios_base::in);
     explicit basic_ifstream(const string& __s, ios_base::openmode __mode = ios_base::in);
+#endif
 #ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
     basic_ifstream(basic_ifstream&& __rhs);
 #endif
@@ -1018,8 +1024,10 @@
 
     basic_filebuf<char_type, traits_type>* rdbuf() const;
     bool is_open() const;
+#ifdef _LIBCPP_HAS_GLOBAL_FILESYSTEM_NAMESPACE
     void open(const char* __s, ios_base::openmode __mode = ios_base::in);
     void open(const string& __s, ios_base::openmode __mode = ios_base::in);
+#endif
     void close();
 
 private:
@@ -1033,6 +1041,7 @@
 {
 }
 
+#ifdef _LIBCPP_HAS_GLOBAL_FILESYSTEM_NAMESPACE
 template <class _CharT, class _Traits>
 inline _LIBCPP_INLINE_VISIBILITY
 basic_ifstream<_CharT, _Traits>::basic_ifstream(const char* __s, ios_base::openmode __mode)
@@ -1050,6 +1059,7 @@
     if (__sb_.open(__s, __mode | ios_base::in) == 0)
         this->setstate(ios_base::failbit);
 }
+#endif
 
 #ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
 
@@ -1107,6 +1117,7 @@
     return __sb_.is_open();
 }
 
+#ifdef _LIBCPP_HAS_GLOBAL_FILESYSTEM_NAMESPACE
 template <class _CharT, class _Traits>
 void
 basic_ifstream<_CharT, _Traits>::open(const char* __s, ios_base::openmode __mode)
@@ -1126,6 +1137,7 @@
     else
         this->setstate(ios_base::failbit);
 }
+#endif
 
 template <class _CharT, class _Traits>
 inline _LIBCPP_INLINE_VISIBILITY
@@ -1163,8 +1175,10 @@
 
     basic_filebuf<char_type, traits_type>* rdbuf() const;
     bool is_open() const;
+#ifdef _LIBCPP_HAS_GLOBAL_FILESYSTEM_NAMESPACE
     void open(const char* __s, ios_base::openmode __mode = ios_base::out);
     void open(const string& __s, ios_base::openmode __mode = ios_base::out);
+#endif
     void close();
 
 private:
@@ -1178,6 +1192,7 @@
 {
 }
 
+#ifdef _LIBCPP_HAS_GLOBAL_FILESYSTEM_NAMESPACE
 template <class _CharT, class _Traits>
 inline _LIBCPP_INLINE_VISIBILITY
 basic_ofstream<_CharT, _Traits>::basic_ofstream(const char* __s, ios_base::openmode __mode)
@@ -1195,6 +1210,7 @@
     if (__sb_.open(__s, __mode | ios_base::out) == 0)
         this->setstate(ios_base::failbit);
 }
+#endif
 
 #ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
 
@@ -1252,6 +1268,7 @@
     return __sb_.is_open();
 }
 
+#ifdef _LIBCPP_HAS_GLOBAL_FILESYSTEM_NAMESPACE
 template <class _CharT, class _Traits>
 void
 basic_ofstream<_CharT, _Traits>::open(const char* __s, ios_base::openmode __mode)
@@ -1271,6 +1288,7 @@
     else
         this->setstate(ios_base::failbit);
 }
+#endif
 
 template <class _CharT, class _Traits>
 inline _LIBCPP_INLINE_VISIBILITY
@@ -1295,8 +1313,10 @@
     typedef typename traits_type::off_type off_type;
 
     basic_fstream();
+#ifdef _LIBCPP_HAS_GLOBAL_FILESYSTEM_NAMESPACE
     explicit basic_fstream(const char* __s, ios_base::openmode __mode = ios_base::in | ios_base::out);
     explicit basic_fstream(const string& __s, ios_base::openmode __mode = ios_base::in | ios_base::out);
+#endif
 #ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
     basic_fstream(basic_fstream&& __rhs);
 #endif
@@ -1308,8 +1328,10 @@
 
     basic_filebuf<char_type, traits_type>* rdbuf() const;
     bool is_open() const;
+#ifdef _LIBCPP_HAS_GLOBAL_FILESYSTEM_NAMESPACE
     void open(const char* __s, ios_base::openmode __mode = ios_base::in | ios_base::out);
     void open(const string& __s, ios_base::openmode __mode = ios_base::in | ios_base::out);
+#endif
     void close();
 
 private:
@@ -1323,6 +1345,7 @@
 {
 }
 
+#ifdef _LIBCPP_HAS_GLOBAL_FILESYSTEM_NAMESPACE
 template <class _CharT, class _Traits>
 inline _LIBCPP_INLINE_VISIBILITY
 basic_fstream<_CharT, _Traits>::basic_fstream(const char* __s, ios_base::openmode __mode)
@@ -1340,6 +1363,7 @@
     if (__sb_.open(__s, __mode) == 0)
         this->setstate(ios_base::failbit);
 }
+#endif
 
 #ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
 
@@ -1397,6 +1421,7 @@
     return __sb_.is_open();
 }
 
+#ifdef _LIBCPP_HAS_GLOBAL_FILESYSTEM_NAMESPACE
 template <class _CharT, class _Traits>
 void
 basic_fstream<_CharT, _Traits>::open(const char* __s, ios_base::openmode __mode)
@@ -1416,6 +1441,7 @@
     else
         this->setstate(ios_base::failbit);
 }
+#endif
 
 template <class _CharT, class _Traits>
 inline _LIBCPP_INLINE_VISIBILITY
Index: test/support/platform_support.h
===================================================================
--- test/support/platform_support.h
+++ test/support/platform_support.h
@@ -65,6 +65,7 @@
 }
 #endif
 
+#ifdef _LIBCPP_HAS_GLOBAL_FILESYSTEM_NAMESPACE
 inline
 std::string
 get_temp_file_name()
@@ -90,5 +91,6 @@
     return Name;
 #endif
 }
+#endif // _LIBCPP_HAS_GLOBAL_FILESYSTEM_NAMESPACE
 
 #endif // PLATFORM_SUPPORT_H