diff --git a/src/pkg/runtime/memclr_386.s b/src/pkg/runtime/memclr_386.s
index 09b35d7e3c9..4b7580cb49f 100644
--- a/src/pkg/runtime/memclr_386.s
+++ b/src/pkg/runtime/memclr_386.s
@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// +build !plan9
+
 #include "../../cmd/ld/textflag.h"
 
 // void runtime·memclr(void*, uintptr)
diff --git a/src/pkg/runtime/memclr_amd64.s b/src/pkg/runtime/memclr_amd64.s
index 8953a396b15..6b79363b249 100644
--- a/src/pkg/runtime/memclr_amd64.s
+++ b/src/pkg/runtime/memclr_amd64.s
@@ -2,6 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
+// +build !plan9
+
 #include "../../cmd/ld/textflag.h"
 
 // void runtime·memclr(void*, uintptr)
diff --git a/src/pkg/runtime/memclr_plan9_386.s b/src/pkg/runtime/memclr_plan9_386.s
new file mode 100644
index 00000000000..9b496785a21
--- /dev/null
+++ b/src/pkg/runtime/memclr_plan9_386.s
@@ -0,0 +1,50 @@
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#include "../../cmd/ld/textflag.h"
+
+// void runtime·memclr(void*, uintptr)
+TEXT runtime·memclr(SB), NOSPLIT, $0-8
+	MOVL	ptr+0(FP), DI
+	MOVL	n+4(FP), BX
+	XORL	AX, AX
+
+clr_tail:
+	TESTL	BX, BX
+	JEQ	clr_0
+	CMPL	BX, $2
+	JBE	clr_1or2
+	CMPL	BX, $4
+	JBE	clr_3or4
+	CMPL	BX, $8
+	JBE	clr_5through8
+	CMPL	BX, $16
+	JBE	clr_9through16
+	MOVL	BX, CX
+	SHRL	$2, CX
+	REP
+	STOSL
+	ANDL	$3, BX
+	JNE	clr_tail
+	RET
+
+clr_1or2:
+	MOVB	AX, (DI)
+	MOVB	AX, -1(DI)(BX*1)
+clr_0:
+	RET
+clr_3or4:
+	MOVW	AX, (DI)
+	MOVW	AX, -2(DI)(BX*1)
+	RET
+clr_5through8:
+	MOVL	AX, (DI)
+	MOVL	AX, -4(DI)(BX*1)
+	RET
+clr_9through16:
+	MOVL	AX, (DI)
+	MOVL	AX, 4(DI)
+	MOVL	AX, -8(DI)(BX*1)
+	MOVL	AX, -4(DI)(BX*1)
+	RET
diff --git a/src/pkg/runtime/memclr_plan9_amd64.s b/src/pkg/runtime/memclr_plan9_amd64.s
new file mode 100644
index 00000000000..6b33054f5d5
--- /dev/null
+++ b/src/pkg/runtime/memclr_plan9_amd64.s
@@ -0,0 +1,48 @@
+// Copyright 2014 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+#include "../../cmd/ld/textflag.h"
+
+// void runtime·memclr(void*, uintptr)
+TEXT runtime·memclr(SB), NOSPLIT, $0-16
+	MOVQ	ptr+0(FP), DI
+	MOVQ	n+8(FP), BX
+	XORQ	AX, AX
+
+clr_tail:
+	TESTQ	BX, BX
+	JEQ	clr_0
+	CMPQ	BX, $2
+	JBE	clr_1or2
+	CMPQ	BX, $4
+	JBE	clr_3or4
+	CMPQ	BX, $8
+	JBE	clr_5through8
+	CMPQ	BX, $16
+	JBE	clr_9through16
+	MOVQ	BX, CX
+	SHRQ	$2, CX
+	REP
+	STOSQ
+	ANDQ	$3, BX
+	JNE	clr_tail
+	RET
+
+clr_1or2:
+	MOVB	AX, (DI)
+	MOVB	AX, -1(DI)(BX*1)
+clr_0:
+	RET
+clr_3or4:
+	MOVW	AX, (DI)
+	MOVW	AX, -2(DI)(BX*1)
+	RET
+clr_5through8:
+	MOVL	AX, (DI)
+	MOVL	AX, -4(DI)(BX*1)
+	RET
+clr_9through16:
+	MOVQ	AX, (DI)
+	MOVQ	AX, -8(DI)(BX*1)
+	RET
diff --git a/src/pkg/runtime/memmove_386.s b/src/pkg/runtime/memmove_386.s
index 13d575973a6..3aed8ad07b6 100644
--- a/src/pkg/runtime/memmove_386.s
+++ b/src/pkg/runtime/memmove_386.s
@@ -23,6 +23,8 @@
 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 // THE SOFTWARE.
 
+// +build !plan9
+
 #include "../../cmd/ld/textflag.h"
 
 TEXT runtime·memmove(SB), NOSPLIT, $0-12
diff --git a/src/pkg/runtime/memmove_amd64.s b/src/pkg/runtime/memmove_amd64.s
index f1641cdb287..5895846db6a 100644
--- a/src/pkg/runtime/memmove_amd64.s
+++ b/src/pkg/runtime/memmove_amd64.s
@@ -23,6 +23,8 @@
 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 // THE SOFTWARE.
 
+// +build !plan9
+
 #include "../../cmd/ld/textflag.h"
 
 // void runtime·memmove(void*, void*, uintptr)
diff --git a/src/pkg/runtime/memmove_plan9_386.s b/src/pkg/runtime/memmove_plan9_386.s
new file mode 100644
index 00000000000..187616cd0af
--- /dev/null
+++ b/src/pkg/runtime/memmove_plan9_386.s
@@ -0,0 +1,127 @@
+// Inferno's libkern/memmove-386.s
+// http://code.google.com/p/inferno-os/source/browse/libkern/memmove-386.s
+//
+//         Copyright © 1994-1999 Lucent Technologies Inc.  All rights reserved.
+//         Revisions Copyright © 2000-2007 Vita Nuova Holdings Limited (www.vitanuova.com).  All rights reserved.
+//         Portions Copyright 2009 The Go Authors. All rights reserved.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+#include "../../cmd/ld/textflag.h"
+
+TEXT runtime·memmove(SB), NOSPLIT, $0-12
+	MOVL	to+0(FP), DI
+	MOVL	fr+4(FP), SI
+	MOVL	n+8(FP), BX
+
+	// REP instructions have a high startup cost, so we handle small sizes
+	// with some straightline code.  The REP MOVSL instruction is really fast
+	// for large sizes.  The cutover is approximately 1K.
+tail:
+	TESTL	BX, BX
+	JEQ	move_0
+	CMPL	BX, $2
+	JBE	move_1or2
+	CMPL	BX, $4
+	JBE	move_3or4
+	CMPL	BX, $8
+	JBE	move_5through8
+	CMPL	BX, $16
+	JBE	move_9through16
+
+/*
+ * check and set for backwards
+ */
+	CMPL	SI, DI
+	JLS	back
+
+/*
+ * forward copy loop
+ */
+forward:	
+	MOVL	BX, CX
+	SHRL	$2, CX
+	ANDL	$3, BX
+
+	REP;	MOVSL
+	JMP	tail
+/*
+ * check overlap
+ */
+back:
+	MOVL	SI, CX
+	ADDL	BX, CX
+	CMPL	CX, DI
+	JLS	forward
+/*
+ * whole thing backwards has
+ * adjusted addresses
+ */
+
+	ADDL	BX, DI
+	ADDL	BX, SI
+	STD
+
+/*
+ * copy
+ */
+	MOVL	BX, CX
+	SHRL	$2, CX
+	ANDL	$3, BX
+
+	SUBL	$4, DI
+	SUBL	$4, SI
+	REP;	MOVSL
+
+	CLD
+	ADDL	$4, DI
+	ADDL	$4, SI
+	SUBL	BX, DI
+	SUBL	BX, SI
+	JMP	tail
+
+move_1or2:
+	MOVB	(SI), AX
+	MOVB	-1(SI)(BX*1), CX
+	MOVB	AX, (DI)
+	MOVB	CX, -1(DI)(BX*1)
+move_0:
+	RET
+move_3or4:
+	MOVW	(SI), AX
+	MOVW	-2(SI)(BX*1), CX
+	MOVW	AX, (DI)
+	MOVW	CX, -2(DI)(BX*1)
+	RET
+move_5through8:
+	MOVL	(SI), AX
+	MOVL	-4(SI)(BX*1), CX
+	MOVL	AX, (DI)
+	MOVL	CX, -4(DI)(BX*1)
+	RET
+move_9through16:
+	MOVL	(SI), AX
+	MOVL	4(SI), CX
+	MOVL	-8(SI)(BX*1), DX
+	MOVL	-4(SI)(BX*1), BP
+	MOVL	AX, (DI)
+	MOVL	CX, 4(DI)
+	MOVL	DX, -8(DI)(BX*1)
+	MOVL	BP, -4(DI)(BX*1)
+	RET
diff --git a/src/pkg/runtime/memmove_plan9_amd64.s b/src/pkg/runtime/memmove_plan9_amd64.s
new file mode 100644
index 00000000000..60108273cf0
--- /dev/null
+++ b/src/pkg/runtime/memmove_plan9_amd64.s
@@ -0,0 +1,126 @@
+// Derived from Inferno's libkern/memmove-386.s (adapted for amd64)
+// http://code.google.com/p/inferno-os/source/browse/libkern/memmove-386.s
+//
+//         Copyright © 1994-1999 Lucent Technologies Inc.  All rights reserved.
+//         Revisions Copyright © 2000-2007 Vita Nuova Holdings Limited (www.vitanuova.com).  All rights reserved.
+//         Portions Copyright 2009 The Go Authors. All rights reserved.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+#include "../../cmd/ld/textflag.h"
+
+// void runtime·memmove(void*, void*, uintptr)
+TEXT runtime·memmove(SB), NOSPLIT, $0-24
+
+	MOVQ	to+0(FP), DI
+	MOVQ	fr+8(FP), SI
+	MOVQ	n+16(FP), BX
+
+	// REP instructions have a high startup cost, so we handle small sizes
+	// with some straightline code.  The REP MOVSQ instruction is really fast
+	// for large sizes.  The cutover is approximately 1K.
+tail:
+	TESTQ	BX, BX
+	JEQ	move_0
+	CMPQ	BX, $2
+	JBE	move_1or2
+	CMPQ	BX, $4
+	JBE	move_3or4
+	CMPQ	BX, $8
+	JBE	move_5through8
+	CMPQ	BX, $16
+	JBE	move_9through16
+
+/*
+ * check and set for backwards
+ */
+	CMPQ	SI, DI
+	JLS	back
+
+/*
+ * forward copy loop
+ */
+forward:
+	MOVQ	BX, CX
+	SHRQ	$3, CX
+	ANDQ	$7, BX
+
+	REP;	MOVSQ
+	JMP	tail
+
+back:
+/*
+ * check overlap
+ */
+	MOVQ	SI, CX
+	ADDQ	BX, CX
+	CMPQ	CX, DI
+	JLS	forward
+	
+/*
+ * whole thing backwards has
+ * adjusted addresses
+ */
+	ADDQ	BX, DI
+	ADDQ	BX, SI
+	STD
+
+/*
+ * copy
+ */
+	MOVQ	BX, CX
+	SHRQ	$3, CX
+	ANDQ	$7, BX
+
+	SUBQ	$8, DI
+	SUBQ	$8, SI
+	REP;	MOVSQ
+
+	CLD
+	ADDQ	$8, DI
+	ADDQ	$8, SI
+	SUBQ	BX, DI
+	SUBQ	BX, SI
+	JMP	tail
+
+move_1or2:
+	MOVB	(SI), AX
+	MOVB	-1(SI)(BX*1), CX
+	MOVB	AX, (DI)
+	MOVB	CX, -1(DI)(BX*1)
+move_0:
+	RET
+move_3or4:
+	MOVW	(SI), AX
+	MOVW	-2(SI)(BX*1), CX
+	MOVW	AX, (DI)
+	MOVW	CX, -2(DI)(BX*1)
+	RET
+move_5through8:
+	MOVL	(SI), AX
+	MOVL	-4(SI)(BX*1), CX
+	MOVL	AX, (DI)
+	MOVL	CX, -4(DI)(BX*1)
+	RET
+move_9through16:
+	MOVQ	(SI), AX
+	MOVQ	-8(SI)(BX*1), CX
+	MOVQ	AX, (DI)
+	MOVQ	CX, -8(DI)(BX*1)
+	RET