diff --git a/libffi/ChangeLog b/libffi/ChangeLog
index 53990f48fad7..69c9e00ef0e7 100644
--- a/libffi/ChangeLog
+++ b/libffi/ChangeLog
@@ -1,3 +1,10 @@
+2011-02-07  Joel Sherrill <joel.sherrill@oarcorp.com>
+
+	* configure.ac: Add mips*-*-rtems* support.
+	* configure: Regenerate.
+	* src/mips/ffitarget.h: Ensure needed constants are available
+	for targets which do not have sgidefs.h.
+
 2011-01-26  Dave Korn  <dave.korn.cygwin@gmail.com>
 
 	PR target/40125
diff --git a/libffi/configure b/libffi/configure
index a4a4a1932cac..b115511dd6c8 100755
--- a/libffi/configure
+++ b/libffi/configure
@@ -11391,7 +11391,7 @@ case "$host" in
 	TARGET=M68K; TARGETDIR=m68k
 	;;
 
-  mips-sgi-irix5.* | mips-sgi-irix6.*)
+  mips-sgi-irix5.* | mips-sgi-irix6.* | mips*-*-rtems*)
 	TARGET=MIPS; TARGETDIR=mips
 	;;
   mips*-*-linux*)
diff --git a/libffi/configure.ac b/libffi/configure.ac
index a7e97d5ec713..d16155a40fb8 100644
--- a/libffi/configure.ac
+++ b/libffi/configure.ac
@@ -114,7 +114,7 @@ case "$host" in
 	TARGET=M68K; TARGETDIR=m68k
 	;;
 
-  mips-sgi-irix5.* | mips-sgi-irix6.*)
+  mips-sgi-irix5.* | mips-sgi-irix6.* | mips*-*-rtems*)
 	TARGET=MIPS; TARGETDIR=mips
 	;;
   mips*-*-linux*)
diff --git a/libffi/src/mips/ffitarget.h b/libffi/src/mips/ffitarget.h
index c5f4e0568416..d0fc983a74f8 100644
--- a/libffi/src/mips/ffitarget.h
+++ b/libffi/src/mips/ffitarget.h
@@ -29,9 +29,17 @@
 
 #ifdef linux
 # include <asm/sgidefs.h>
+#elif defined(__rtems__)
+/*
+ * Subprogram calling convention - copied from sgidefs.h
+ */
+#define _MIPS_SIM_ABI32		1
+#define _MIPS_SIM_NABI32	2
+#define _MIPS_SIM_ABI64		3
 #else
 # include <sgidefs.h>
 #endif
+
 #  ifndef _ABIN32
 #    define _ABIN32 _MIPS_SIM_NABI32
 #  endif