diff --git a/newlib/configure b/newlib/configure
index 2ac07fe06..de28c25b3 100755
--- a/newlib/configure
+++ b/newlib/configure
@@ -802,6 +802,7 @@ enable_newlib_nano_malloc
 enable_newlib_unbuf_stream_opt
 enable_lite_exit
 enable_newlib_nano_formatted_io
+enable_newlib_retargetable_locking
 enable_multilib
 enable_target_optspace
 enable_malloc_debugging
@@ -1473,6 +1474,7 @@ Optional Features:
   --disable-newlib-unbuf-stream-opt    disable unbuffered stream optimization in streamio
   --enable-lite-exit	enable light weight exit
   --enable-newlib-nano-formatted-io    Use nano version formatted IO
+  --enable-newlib-retargetable-locking    Allow locking routines to be retargeted at link time
   --enable-multilib         build many library versions (default)
   --enable-target-optspace  optimize for space
   --enable-malloc-debugging indicate malloc debugging requested
@@ -2474,6 +2476,18 @@ else
 fi
 
 
+# Check whether --enable-newlib-retargetable-locking was given.
+if test "${enable_newlib_retargetable_locking+set}" = set; then :
+  enableval=$enable_newlib_retargetable_locking; case "${enableval}" in
+   yes) newlib_retargetable_locking=yes ;;
+   no)  newlib_retargetable_locking=no ;;
+   *) as_fn_error $? "bad value ${enableval} for newlib-retargetable-locking" "$LINENO" 5 ;;
+ esac
+else
+  newlib_retargetable_locking=no
+fi
+
+
 
 # Make sure we can run config.sub.
 $SHELL "$ac_aux_dir/config.sub" sun4 >/dev/null 2>&1 ||
@@ -11780,7 +11794,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11783 "configure"
+#line 11797 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -11886,7 +11900,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11889 "configure"
+#line 11903 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -12455,6 +12469,13 @@ _ACEOF
 
 fi
 
+if test "${newlib_retargetable_locking}" = "yes"; then
+cat >>confdefs.h <<_ACEOF
+#define _RETARGETABLE_LOCKING 1
+_ACEOF
+
+fi
+
 
 if test "x${iconv_encodings}" != "x" \
    || test "x${iconv_to_encodings}" != "x" \
diff --git a/newlib/configure.in b/newlib/configure.in
index bfaf038c7..354c07ca5 100644
--- a/newlib/configure.in
+++ b/newlib/configure.in
@@ -218,6 +218,17 @@ AC_ARG_ENABLE(newlib_nano_formatted_io,
    *) AC_MSG_ERROR(bad value ${enableval} for newlib-nano-formatted-io) ;;
  esac],[newlib_nano_formatted_io=no])
 
+dnl Support --enable-retargetable-locking
+dnl This option is also read in libc/configure.in.  It is repeated
+dnl here so that it shows up in the help text.
+AC_ARG_ENABLE(newlib-retargetable-locking,
+[  --enable-newlib-retargetable-locking    Allow locking routines to be retargeted at link time],
+[case "${enableval}" in
+   yes) newlib_retargetable_locking=yes ;;
+   no)  newlib_retargetable_locking=no ;;
+   *) AC_MSG_ERROR(bad value ${enableval} for newlib-retargetable-locking) ;;
+ esac],[newlib_retargetable_locking=no])
+
 NEWLIB_CONFIGURE(.)
 
 dnl We have to enable libtool after NEWLIB_CONFIGURE because if we try and
@@ -458,6 +469,10 @@ if test "${newlib_nano_formatted_io}" = "yes"; then
 AC_DEFINE_UNQUOTED(_NANO_FORMATTED_IO)
 fi
 
+if test "${newlib_retargetable_locking}" = "yes"; then
+AC_DEFINE_UNQUOTED(_RETARGETABLE_LOCKING)
+fi
+
 dnl
 dnl Parse --enable-newlib-iconv-encodings option argument
 dnl
diff --git a/newlib/libc/configure b/newlib/libc/configure
index 4dc4d1bf7..dabe44fd9 100755
--- a/newlib/libc/configure
+++ b/newlib/libc/configure
@@ -751,6 +751,8 @@ build
 newlib_basedir
 MAY_SUPPLY_SYSCALLS_FALSE
 MAY_SUPPLY_SYSCALLS_TRUE
+NEWLIB_RETARGETABLE_LOCKING_FALSE
+NEWLIB_RETARGETABLE_LOCKING_TRUE
 NEWLIB_NANO_FORMATTED_IO_FALSE
 NEWLIB_NANO_FORMATTED_IO_TRUE
 target_alias
@@ -797,6 +799,7 @@ enable_option_checking
 enable_newlib_io_pos_args
 enable_newlib_nano_malloc
 enable_newlib_nano_formatted_io
+enable_newlib_retargetable_locking
 enable_multilib
 enable_target_optspace
 enable_malloc_debugging
@@ -1448,6 +1451,7 @@ Optional Features:
   --enable-newlib-io-pos-args enable printf-family positional arg support
   --enable-newlib-nano-malloc    Use small-footprint nano-malloc implementation
   --enable-newlib-nano-formatted-io    Use small-footprint nano-formatted-IO implementation
+  --enable-newlib-retargetable-locking    Allow locking routines to be retargeted at link time
   --enable-multilib         build many library versions (default)
   --enable-target-optspace  optimize for space
   --enable-malloc-debugging indicate malloc debugging requested
@@ -2252,6 +2256,26 @@ else
 fi
 
 
+# Check whether --enable-newlib-retargetable-locking was given.
+if test "${enable_newlib_retargetable_locking+set}" = set; then :
+  enableval=$enable_newlib_retargetable_locking; case "${enableval}" in
+   yes) newlib_retargetable_locking=yes ;;
+   no)  newlib_retargetable_lock=no ;;
+   *) as_fn_error $? "bad value ${enableval} for newlib-retargetable-locking" "$LINENO" 5 ;;
+ esac
+else
+  newlib_retargetable_locking=no
+fi
+
+ if test x$newlib_retargetable_locking = xyes; then
+  NEWLIB_RETARGETABLE_LOCKING_TRUE=
+  NEWLIB_RETARGETABLE_LOCKING_FALSE='#'
+else
+  NEWLIB_RETARGETABLE_LOCKING_TRUE='#'
+  NEWLIB_RETARGETABLE_LOCKING_FALSE=
+fi
+
+
 
 # Make sure we can run config.sub.
 $SHELL "$ac_aux_dir/config.sub" sun4 >/dev/null 2>&1 ||
@@ -11525,7 +11549,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11528 "configure"
+#line 11552 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -11631,7 +11655,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 11634 "configure"
+#line 11658 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -12248,6 +12272,10 @@ if test -z "${NEWLIB_NANO_FORMATTED_IO_TRUE}" && test -z "${NEWLIB_NANO_FORMATTE
   as_fn_error $? "conditional \"NEWLIB_NANO_FORMATTED_IO\" was never defined.
 Usually this means the macro was only invoked conditionally." "$LINENO" 5
 fi
+if test -z "${NEWLIB_RETARGETABLE_LOCKING_TRUE}" && test -z "${NEWLIB_RETARGETABLE_LOCKING_FALSE}"; then
+  as_fn_error $? "conditional \"NEWLIB_RETARGETABLE_LOCKING\" was never defined.
+Usually this means the macro was only invoked conditionally." "$LINENO" 5
+fi
 if test -z "${MAY_SUPPLY_SYSCALLS_TRUE}" && test -z "${MAY_SUPPLY_SYSCALLS_FALSE}"; then
   as_fn_error $? "conditional \"MAY_SUPPLY_SYSCALLS\" was never defined.
 Usually this means the macro was only invoked conditionally." "$LINENO" 5
diff --git a/newlib/libc/configure.in b/newlib/libc/configure.in
index 0a7bb8815..ac25a3933 100644
--- a/newlib/libc/configure.in
+++ b/newlib/libc/configure.in
@@ -36,6 +36,16 @@ AC_ARG_ENABLE(newlib_nano_formatted_io,
  esac],[newlib_nano_formatted_io=no])
 AM_CONDITIONAL(NEWLIB_NANO_FORMATTED_IO, test x$newlib_nano_formatted_io = xyes)
 
+dnl Support --enable-retargetable-locking used by libc/sys
+AC_ARG_ENABLE(newlib-retargetable-locking,
+[  --enable-newlib-retargetable-locking    Allow locking routines to be retargeted at link time],
+[case "${enableval}" in
+   yes) newlib_retargetable_locking=yes ;;
+   no)  newlib_retargetable_lock=no ;;
+   *) AC_MSG_ERROR(bad value ${enableval} for newlib-retargetable-locking) ;;
+ esac],[newlib_retargetable_locking=no])
+AM_CONDITIONAL(NEWLIB_RETARGETABLE_LOCKING, test x$newlib_retargetable_locking = xyes)
+
 NEWLIB_CONFIGURE(..)
 
 AM_CONDITIONAL(NEWLIB_NANO_MALLOC, test x$newlib_nano_malloc = xyes)
diff --git a/newlib/libc/include/sys/lock.h b/newlib/libc/include/sys/lock.h
index 9075e35c9..42f9c4cd9 100644
--- a/newlib/libc/include/sys/lock.h
+++ b/newlib/libc/include/sys/lock.h
@@ -3,10 +3,13 @@
 
 /* dummy lock routines for single-threaded aps */
 
+#include <newlib.h>
+#include <_ansi.h>
+
+#if !defined(_RETARGETABLE_LOCKING)
+
 typedef int _LOCK_T;
 typedef int _LOCK_RECURSIVE_T;
- 
-#include <_ansi.h>
 
 #define __LOCK_INIT(class,lock) static int lock = 0;
 #define __LOCK_INIT_RECURSIVE(class,lock) static int lock = 0;
@@ -21,4 +24,46 @@ typedef int _LOCK_RECURSIVE_T;
 #define __lock_release(lock) (_CAST_VOID 0)
 #define __lock_release_recursive(lock) (_CAST_VOID 0)
 
+#else
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+struct __lock;
+typedef struct __lock * _LOCK_T;
+#define _LOCK_RECURSIVE_T _LOCK_T
+
+#define __LOCK_INIT(class,lock) extern struct __lock __lock_ ## lock; \
+	class _LOCK_T lock = &__lock_ ## lock
+#define __LOCK_INIT_RECURSIVE(class,lock) __LOCK_INIT(class,lock)
+
+extern void __retarget_lock_init(_LOCK_T *lock);
+#define __lock_init(lock) __retarget_lock_init(&lock)
+extern void __retarget_lock_init_recursive(_LOCK_T *lock);
+#define __lock_init_recursive(lock) __retarget_lock_init_recursive(&lock)
+extern void __retarget_lock_close(_LOCK_T lock);
+#define __lock_close(lock) __retarget_lock_close(lock)
+extern void __retarget_lock_close_recursive(_LOCK_T lock);
+#define __lock_close_recursive(lock) __retarget_lock_close_recursive(lock)
+extern void __retarget_lock_acquire(_LOCK_T lock);
+#define __lock_acquire(lock) __retarget_lock_acquire(lock)
+extern void __retarget_lock_acquire_recursive(_LOCK_T lock);
+#define __lock_acquire_recursive(lock) __retarget_lock_acquire_recursive(lock)
+extern int __retarget_lock_try_acquire(_LOCK_T lock);
+#define __lock_try_acquire(lock) __retarget_lock_try_acquire(lock)
+extern int __retarget_lock_try_acquire_recursive(_LOCK_T lock);
+#define __lock_try_acquire_recursive(lock) \
+  __retarget_lock_try_acquire_recursive(lock)
+extern void __retarget_lock_release(_LOCK_T lock);
+#define __lock_release(lock) __retarget_lock_release(lock)
+extern void __retarget_lock_release_recursive(_LOCK_T lock);
+#define __lock_release_recursive(lock) __retarget_lock_release_recursive(lock)
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* !defined(_RETARGETABLE_LOCKING) */
+
 #endif /* __SYS_LOCK_H__ */
diff --git a/newlib/libc/misc/Makefile.am b/newlib/libc/misc/Makefile.am
index 3fe8e55f5..7571ef263 100644
--- a/newlib/libc/misc/Makefile.am
+++ b/newlib/libc/misc/Makefile.am
@@ -6,6 +6,11 @@ INCLUDES = $(NEWLIB_CFLAGS) $(CROSS_CFLAGS) $(TARGET_CFLAGS)
 
 LIB_SOURCES = __dprintf.c unctrl.c ffs.c init.c fini.c
 
+if NEWLIB_RETARGETABLE_LOCKING
+LIB_SOURCES += \
+	lock.c
+endif
+
 libmisc_la_LDFLAGS = -Xcompiler -nostdlib
 
 if USE_LIBTOOL
@@ -21,5 +26,5 @@ endif # USE_LIBTOOL
 
 include $(srcdir)/../../Makefile.shared
 
-CHEWOUT_FILES = unctrl.def ffs.def
+CHEWOUT_FILES = unctrl.def lock.def ffs.def
 CHAPTERS = misc.tex
diff --git a/newlib/libc/misc/Makefile.in b/newlib/libc/misc/Makefile.in
index 0ada8de34..e7925231c 100644
--- a/newlib/libc/misc/Makefile.in
+++ b/newlib/libc/misc/Makefile.in
@@ -53,6 +53,9 @@ PRE_UNINSTALL = :
 POST_UNINSTALL = :
 build_triplet = @build@
 host_triplet = @host@
+@NEWLIB_RETARGETABLE_LOCKING_TRUE@am__append_1 = \
+@NEWLIB_RETARGETABLE_LOCKING_TRUE@	lock.c
+
 DIST_COMMON = $(srcdir)/../../Makefile.shared $(srcdir)/Makefile.in \
 	$(srcdir)/Makefile.am
 subdir = misc
@@ -72,14 +75,19 @@ LIBRARIES = $(noinst_LIBRARIES)
 ARFLAGS = cru
 lib_a_AR = $(AR) $(ARFLAGS)
 lib_a_LIBADD =
-am__objects_1 = lib_a-__dprintf.$(OBJEXT) lib_a-unctrl.$(OBJEXT) \
-	lib_a-ffs.$(OBJEXT) lib_a-init.$(OBJEXT) lib_a-fini.$(OBJEXT)
-@USE_LIBTOOL_FALSE@am_lib_a_OBJECTS = $(am__objects_1)
+@NEWLIB_RETARGETABLE_LOCKING_TRUE@am__objects_1 =  \
+@NEWLIB_RETARGETABLE_LOCKING_TRUE@	lib_a-lock.$(OBJEXT)
+am__objects_2 = lib_a-__dprintf.$(OBJEXT) lib_a-unctrl.$(OBJEXT) \
+	lib_a-ffs.$(OBJEXT) lib_a-init.$(OBJEXT) lib_a-fini.$(OBJEXT) \
+	$(am__objects_1)
+@USE_LIBTOOL_FALSE@am_lib_a_OBJECTS = $(am__objects_2)
 lib_a_OBJECTS = $(am_lib_a_OBJECTS)
 LTLIBRARIES = $(noinst_LTLIBRARIES)
 libmisc_la_LIBADD =
-am__objects_2 = __dprintf.lo unctrl.lo ffs.lo init.lo fini.lo
-@USE_LIBTOOL_TRUE@am_libmisc_la_OBJECTS = $(am__objects_2)
+@NEWLIB_RETARGETABLE_LOCKING_TRUE@am__objects_3 = lock.lo
+am__objects_4 = __dprintf.lo unctrl.lo ffs.lo init.lo fini.lo \
+	$(am__objects_3)
+@USE_LIBTOOL_TRUE@am_libmisc_la_OBJECTS = $(am__objects_4)
 libmisc_la_OBJECTS = $(am_libmisc_la_OBJECTS)
 libmisc_la_LINK = $(LIBTOOL) --tag=CC $(AM_LIBTOOLFLAGS) \
 	$(LIBTOOLFLAGS) --mode=link $(CCLD) $(AM_CFLAGS) $(CFLAGS) \
@@ -252,7 +260,7 @@ top_builddir = @top_builddir@
 top_srcdir = @top_srcdir@
 AUTOMAKE_OPTIONS = cygnus
 INCLUDES = $(NEWLIB_CFLAGS) $(CROSS_CFLAGS) $(TARGET_CFLAGS)
-LIB_SOURCES = __dprintf.c unctrl.c ffs.c init.c fini.c
+LIB_SOURCES = __dprintf.c unctrl.c ffs.c init.c fini.c $(am__append_1)
 libmisc_la_LDFLAGS = -Xcompiler -nostdlib
 @USE_LIBTOOL_TRUE@noinst_LTLIBRARIES = libmisc.la
 @USE_LIBTOOL_TRUE@libmisc_la_SOURCES = $(LIB_SOURCES)
@@ -271,7 +279,7 @@ DOCBOOK_CHEW = ${top_srcdir}/../doc/makedocbook.py
 DOCBOOK_OUT_FILES = $(CHEWOUT_FILES:.def=.xml)
 DOCBOOK_CHAPTERS = $(CHAPTERS:.tex=.xml)
 CLEANFILES = $(CHEWOUT_FILES) $(CHEWOUT_FILES:.def=.ref) $(DOCBOOK_OUT_FILES)
-CHEWOUT_FILES = unctrl.def ffs.def
+CHEWOUT_FILES = unctrl.def lock.def ffs.def
 CHAPTERS = misc.tex
 all: all-am
 
@@ -372,6 +380,12 @@ lib_a-fini.o: fini.c
 lib_a-fini.obj: fini.c
 	$(CC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(AM_CPPFLAGS) $(CPPFLAGS) $(lib_a_CFLAGS) $(CFLAGS) -c -o lib_a-fini.obj `if test -f 'fini.c'; then $(CYGPATH_W) 'fini.c'; else $(CYGPATH_W) '$(srcdir)/fini.c'; fi`
 
+lib_a-lock.o: lock.c
+	$(CC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(AM_CPPFLAGS) $(CPPFLAGS) $(lib_a_CFLAGS) $(CFLAGS) -c -o lib_a-lock.o `test -f 'lock.c' || echo '$(srcdir)/'`lock.c
+
+lib_a-lock.obj: lock.c
+	$(CC) $(DEFS) $(DEFAULT_INCLUDES) $(INCLUDES) $(AM_CPPFLAGS) $(CPPFLAGS) $(lib_a_CFLAGS) $(CFLAGS) -c -o lib_a-lock.obj `if test -f 'lock.c'; then $(CYGPATH_W) 'lock.c'; else $(CYGPATH_W) '$(srcdir)/lock.c'; fi`
+
 mostlyclean-libtool:
 	-rm -f *.lo
 
diff --git a/newlib/libc/misc/lock.c b/newlib/libc/misc/lock.c
new file mode 100644
index 000000000..a76317668
--- /dev/null
+++ b/newlib/libc/misc/lock.c
@@ -0,0 +1,157 @@
+/*
+FUNCTION
+<<__retarget_lock_init>>, <<__retarget_lock_init_recursive>>, <<__retarget_lock_close>>, <<__retarget_lock_close_recursive>>, <<__retarget_lock_acquire>>, <<__retarget_lock_acquire_recursive>>, <<__retarget_lock_try_acquire>>, <<__retarget_lock_try_acquire_recursive>>, <<__retarget_lock_release>>, <<__retarget_lock_release_recursive>>---locking routines
+
+INDEX
+	__lock___sinit_recursive_mutex
+INDEX
+	__lock___sfp_recursive_mutex
+INDEX
+	__lock___atexit_recursive_mutex
+INDEX
+	__lock___at_quick_exit_mutex
+INDEX
+	__lock___malloc_recursive_mutex
+INDEX
+	__lock___env_recursive_mutex
+INDEX
+	__lock___tz_mutex
+INDEX
+	__lock___dd_hash_mutex
+INDEX
+	__lock___arc4random_mutex
+
+INDEX
+	__retarget_lock_init
+INDEX
+	__retarget_lock_init_recursive
+INDEX
+	__retarget_lock_close
+INDEX
+	__retarget_lock_close_recursive
+INDEX
+	__retarget_lock_acquire
+INDEX
+	__retarget_lock_acquire_recursive
+INDEX
+	__retarget_lock_try_acquire
+INDEX
+	__retarget_lock_try_acquire_recursive
+INDEX
+	__retarget_lock_release
+INDEX
+	__retarget_lock_release_recursive
+
+ANSI_SYNOPSIS
+	#include <lock.h>
+	struct __lock __lock___sinit_recursive_mutex;
+	struct __lock __lock___sfp_recursive_mutex;
+	struct __lock __lock___atexit_recursive_mutex;
+	struct __lock __lock___at_quick_exit_mutex;
+	struct __lock __lock___malloc_recursive_mutex;
+	struct __lock __lock___env_recursive_mutex;
+	struct __lock __lock___tz_mutex;
+	struct __lock __lock___dd_hash_mutex;
+	struct __lock __lock___arc4random_mutex;
+
+	void __retarget_lock_init (_LOCK_T * <[lock_ptr]>);
+	void __retarget_lock_init_recursive (_LOCK_T * <[lock_ptr]>);
+	void __retarget_lock_close (_LOCK_T <[lock]>);
+	void __retarget_lock_close_recursive (_LOCK_T <[lock]>);
+	void __retarget_lock_acquire (_LOCK_T <[lock]>);
+	void __retarget_lock_acquire_recursive (_LOCK_T <[lock]>);
+	int __retarget_lock_try_acquire (_LOCK_T <[lock]>);
+	int __retarget_lock_try_acquire_recursive (_LOCK_T <[lock]>);
+	void __retarget_lock_release (_LOCK_T <[lock]>);
+	void __retarget_lock_release_recursive (_LOCK_T <[lock]>);
+
+DESCRIPTION
+Newlib was configured to allow the target platform to provide the locking
+routines and static locks at link time.  As such, a dummy default
+implementation of these routines and static locks is provided for
+single-threaded application to link successfully out of the box on bare-metal
+systems.
+
+For multi-threaded applications the target platform is required to provide
+an implementation for @strong{all} these routines and static locks.  If some
+routines or static locks are missing, the link will fail with doubly defined
+symbols.
+
+PORTABILITY
+These locking routines and static lock are newlib-specific.  Supporting OS
+subroutines are required for linking multi-threaded applications.
+*/
+
+/* dummy lock routines and static locks for single-threaded apps */
+
+#ifndef __SINGLE_THREAD__
+
+#include <sys/lock.h>
+
+struct __lock {
+  char unused;
+};
+
+struct __lock __lock___sinit_recursive_mutex;
+struct __lock __lock___sfp_recursive_mutex;
+struct __lock __lock___atexit_recursive_mutex;
+struct __lock __lock___at_quick_exit_mutex;
+struct __lock __lock___malloc_recursive_mutex;
+struct __lock __lock___env_recursive_mutex;
+struct __lock __lock___tz_mutex;
+struct __lock __lock___dd_hash_mutex;
+struct __lock __lock___arc4random_mutex;
+
+void
+__retarget_lock_init (_LOCK_T *lock)
+{
+}
+
+void
+__retarget_lock_init_recursive(_LOCK_T *lock)
+{
+}
+
+void
+__retarget_lock_close(_LOCK_T lock)
+{
+}
+
+void
+__retarget_lock_close_recursive(_LOCK_T lock)
+{
+}
+
+void
+__retarget_lock_acquire (_LOCK_T lock)
+{
+}
+
+void
+__retarget_lock_acquire_recursive (_LOCK_T lock)
+{
+}
+
+int
+__retarget_lock_try_acquire(_LOCK_T lock)
+{
+  return 1;
+}
+
+int
+__retarget_lock_try_acquire_recursive(_LOCK_T lock)
+{
+  return 1;
+}
+
+void
+__retarget_lock_release (_LOCK_T lock)
+{
+}
+
+void
+__retarget_lock_release_recursive (_LOCK_T lock)
+{
+}
+
+#endif /* !defined(__SINGLE_THREAD__) */
diff --git a/newlib/libc/misc/misc.tex b/newlib/libc/misc/misc.tex
index 22c313eb1..248243b53 100644
--- a/newlib/libc/misc/misc.tex
+++ b/newlib/libc/misc/misc.tex
@@ -4,11 +4,15 @@ This chapter describes miscellaneous routines not covered elsewhere.
 
 @menu 
 * ffs::      Return first bit set in a word
+* __retarget_lock_init::     Retargetable locking routines
 * unctrl::   Return printable representation of a character
 @end menu
 
 @page
 @include misc/ffs.def
 
+@page
+@include misc/lock.def
+
 @page
 @include misc/unctrl.def
diff --git a/newlib/newlib.hin b/newlib/newlib.hin
index d03dfac0e..397bc9b96 100644
--- a/newlib/newlib.hin
+++ b/newlib/newlib.hin
@@ -82,6 +82,9 @@
 /* Define if small footprint nano-formatted-IO implementation used.  */
 #undef _NANO_FORMATTED_IO
 
+/* Define if using retargetable functions for default lock routines.  */
+#undef _RETARGETABLE_LOCKING
+
 /*
  * Iconv encodings enabled ("to" direction)
  */