diff --git a/src/cmd/5l/5.out.h b/src/cmd/5l/5.out.h
index ac463b4cdf8..22c675b04d4 100644
--- a/src/cmd/5l/5.out.h
+++ b/src/cmd/5l/5.out.h
@@ -42,6 +42,9 @@
 /* compiler allocates R1 up as temps */
 /* compiler allocates register variables R3 up */
 #define	REGEXT		10
+/* these two registers are declared in runtime.h */
+#define REGG        (REGEXT-0)
+#define REGM        (REGEXT-1)
 /* compiler allocates external registers R10 down */
 #define	REGTMP		11
 #define	REGSB		12
diff --git a/src/cmd/5l/go.c b/src/cmd/5l/go.c
new file mode 100644
index 00000000000..f1146c0c999
--- /dev/null
+++ b/src/cmd/5l/go.c
@@ -0,0 +1,12 @@
+// Copyright 2009 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 "l.h"
+#include "compat.h"
+enum
+{
+	PtrSize = 4
+};
+#define pcond cond
+#include "../ld/go.c"
diff --git a/src/cmd/5l/l.h b/src/cmd/5l/l.h
index b864744e16d..c8c49998e53 100644
--- a/src/cmd/5l/l.h
+++ b/src/cmd/5l/l.h
@@ -161,6 +161,8 @@ struct	Use
 
 enum
 {
+	Sxxx,
+
 	STEXT		= 1,
 	SDATA,
 	SBSS,
@@ -375,7 +377,7 @@ int	Sconv(Fmt*);
 int	aclass(Adr*);
 int	thumbaclass(Adr*, Prog*);
 void	addhist(int32, int);
-void	append(Prog*, Prog*);
+Prog*	appendp(Prog*);
 void	asmb(void);
 void	asmdyn(void);
 void	asmlc(void);
@@ -481,4 +483,13 @@ void	linuxshdr(char *name, uint32 type, vlong flags, vlong addr, vlong off,
 	vlong size, uint32 link, uint32 info, vlong align, vlong entsize);
 int	linuxstrtable(void);
 
+/*
+ *	go.c
+ */
+void	deadcode(void);
+void	definetypestrings(void);
+void	definetypesigs(void);
+char*	gotypefor(char *name);
+void	ldpkg(Biobuf *f, int64 len, char *filename);
+
 #endif
diff --git a/src/cmd/5l/noop.c b/src/cmd/5l/noop.c
index e3207ab46a1..333a3999a3e 100644
--- a/src/cmd/5l/noop.c
+++ b/src/cmd/5l/noop.c
@@ -30,6 +30,12 @@
 
 #include	"l.h"
 
+// see ../../runtime/proc.c:/StackGuard
+enum
+{
+	StackBig = 4096,
+};
+
 static	Sym*	sym_div;
 static	Sym*	sym_divu;
 static	Sym*	sym_mod;
@@ -105,6 +111,8 @@ noops(void)
 {
 	Prog *p, *q, *q1, *q2;
 	int o, curframe, curbecome, maxbecome, foreign;
+	Prog *pmorestack;
+	Sym *symmorestack;
 
 	/*
 	 * find leaf subroutines
@@ -119,6 +127,23 @@ noops(void)
 		Bprint(&bso, "%5.2f noops\n", cputime());
 	Bflush(&bso);
 
+	pmorestack = P;
+	symmorestack = lookup("sys·morestack", 0);
+
+	if(symmorestack->type == STEXT)
+	for(p = firstp; p != P; p = p->link) {
+		if(p->as == ATEXT) {
+			if(p->from.sym == symmorestack) {
+				pmorestack = p;
+				p->reg |= NOSPLIT;
+				break;
+			}
+		}
+	}
+	// TODO(kaib): make lack of morestack an error
+// 	if(pmorestack == P)
+// 		diag("sys·morestack not defined");
+
 	curframe = 0;
 	curbecome = 0;
 	maxbecome = 0;
@@ -281,27 +306,13 @@ noops(void)
 			if(curtext->mark & LEAF) {
 				if(curtext->from.sym)
 					curtext->from.sym->type = SLEAF;
-#ifdef optimise_time
-				if(autosize) {
-					q = prg();
-					q->as = ASUB;
-					q->line = p->line;
-					q->from.type = D_CONST;
-					q->from.offset = autosize;
-					q->to.type = D_REG;
-					q->to.reg = REGSP;
-
-					q->link = p->link;
-					p->link = q;
-				}
-				break;
-#else
 				if(!autosize)
 					break;
-#endif
 			}
 
 			if(thumb){
+				if(!(p->reg & NOSPLIT))
+					diag("stack splitting not supported in thumb");
 				if(!(curtext->mark & LEAF)){
 					q = movrr(nil, REGLINK, REGTMPT-1, p);
 					p->link = q;
@@ -331,17 +342,75 @@ noops(void)
 				break;
 			}
 
-			q1 = prg();
-			q1->as = AMOVW;
-			q1->scond |= C_WBIT;
-			q1->line = p->line;
-			q1->from.type = D_REG;
-			q1->from.reg = REGLINK;
-			q1->to.type = D_OREG;
-			q1->to.offset = -autosize;
-			q1->to.reg = REGSP;
-			q1->link = p->link;
-			p->link = q1;
+// 			if(p->reg & NOSPLIT) {
+			if(1) {
+				q1 = prg();
+				q1->as = AMOVW;
+				q1->scond |= C_WBIT;
+				q1->line = p->line;
+				q1->from.type = D_REG;
+				q1->from.reg = REGLINK;
+				q1->to.type = D_OREG;
+				q1->to.offset = -autosize;
+				q1->to.reg = REGSP;
+				q1->link = p->link;
+				p->link = q1;
+			} else { // !NOSPLIT
+				// split stack check
+				if(autosize < StackBig) {
+					p = appendp(p); // load G.stackguard into R1
+					p->as = AMOVW;
+					p->from.type = D_OREG;
+					p->from.reg = REGG;
+					p->to.type = D_REG;
+					p->to.reg = 1;
+
+					p = appendp(p);
+					p->as = ACMP;
+					p->from.type = D_REG;
+					p->from.reg = 1;
+					p->from.offset = -autosize;
+					p->reg = REGSP;
+				}
+
+				// TODO(kaib): Optimize the heck out of this
+				p = appendp(p); // store autosize in M.morearg
+				p->as = AMOVW;
+				p->from.type = D_CONST;
+				if(autosize+160 > 4096)
+					p->from.offset = (autosize+160) & ~7LL;
+				p->to.type = D_REG;
+				p->to.reg = REGTMP;
+
+				p = appendp(p);
+				p->as = AMOVW;
+				p->from.type = D_REG;
+				p->from.reg = REGTMP;
+				p->to.type = D_OREG;
+				p->to.reg = REGM;
+				p->to.offset = 4;
+
+				p = appendp(p);
+				p->as = AMOVW;
+				p->from.type = D_CONST;
+// 				p->from.offset = curtext->to.offset2;
+				p->to.type = D_REG;
+				p->to.reg = REGTMP;
+
+				p = appendp(p);
+				p->as = AMOVW;
+				p->from.type = D_REG;
+				p->from.reg = REGTMP;
+				p->to.type = D_OREG;
+				p->to.reg = REGM;
+				p->to.offset = 8;
+ 
+// 				p = appendp(p);
+// 				p->as = ABL;
+// 				p->to.type = D_BRANCH;
+// 				p->to.sym = symmorestack;
+// 				p->cond = pmorestack;
+			}
 			break;
 
 		case ARET:
@@ -364,31 +433,6 @@ noops(void)
 					p->to.reg = REGLINK;
 					break;
 				}
-
-#ifdef optimise_time
-				p->as = AADD;
-				p->from.type = D_CONST;
-				p->from.offset = autosize;
-				p->to.type = D_REG;
-				p->to.reg = REGSP;
-				if(thumb){
-					p->link = fnret(nil, REGLINK, foreign, p);
-					break;
-				}
-				q = prg();
-// if(foreign) print("ABXRET 2 %s\n", curtext->from.sym->name);
-				q->as = foreign ? ABXRET : AB;
-				q->scond = p->scond;
-				q->line = p->line;
-				q->to.type = D_OREG;
-				q->to.offset = 0;
-				q->to.reg = REGLINK;
-
-				q->link = p->link;
-				p->link = q;
-
-				break;
-#endif
 			}
 			if(thumb){
 				if(curtext->mark & LEAF){
@@ -491,28 +535,6 @@ noops(void)
 					p->from = zprg.from;
 					break;
 				}
-
-#ifdef optimise_time
-				q = prg();
-				q->scond = p->scond;
-				q->line = p->line;
-				q->as = AB;
-				q->from = zprg.from;
-				q->to = p->to;
-				q->cond = p->cond;
-				q->link = p->link;
-				p->link = q;
-
-				p->as = AADD;
-				p->from = zprg.from;
-				p->from.type = D_CONST;
-				p->from.offset = autosize;
-				p->to = zprg.to;
-				p->to.type = D_REG;
-				p->to.reg = REGSP;
-
-				break;
-#endif
 			}
 			q = prg();
 			q->scond = p->scond;
diff --git a/src/cmd/5l/obj.c b/src/cmd/5l/obj.c
index 30f60e07dd3..3295348c23c 100644
--- a/src/cmd/5l/obj.c
+++ b/src/cmd/5l/obj.c
@@ -278,6 +278,11 @@ main(int argc, char *argv[])
 		sprint(a, "%s/pkg/%s_%s/runtime.a", goroot, goos, goarch);
 		objfile(a);
 	}
+	// TODO(kaib): add these go specific extensions
+// 	definetypestrings();
+// 	definetypesigs();
+// 	deadcode();
+
 	firstp = firstp->link;
 	if(firstp == P)
 		goto out;
@@ -764,8 +769,10 @@ ldobj(Biobuf *f, int32 len, char *pn)
 	uint32 sig;
 	static int files;
 	static char **filen;
-	char **nfilen,*name;
-	vlong eof;
+	char **nfilen, *line, *name;
+	int n, c1, c2, c3;
+	int32 eof;
+	int32 start, import0, import1;
 
 	eof = Boffset(f) + len;
 
@@ -779,6 +786,48 @@ ldobj(Biobuf *f, int32 len, char *pn)
 
 	di = S;
 
+	goto newloop;
+
+	/* check the header */
+	start = Boffset(f);
+	line = Brdline(f, '\n');
+	if(line == nil) {
+		if(Blinelen(f) > 0) {
+			diag("%s: malformed object file", pn);
+			return;
+		}
+		goto eof;
+	}
+	n = Blinelen(f) - 1;
+	if(n != strlen(thestring) || strncmp(line, thestring, n) != 0) {
+		if(line)
+			line[n] = '\0';
+		diag("file not %s [%s]\n", thestring, line);
+	// TODO(kaib): Make not finding the header an error again
+// 		return;
+		Bseek(f, start, 0);
+		goto newloop;
+	}
+
+	/* skip over exports and other info -- ends with \n!\n */
+	import0 = Boffset(f);
+	c1 = '\n';	// the last line ended in \n
+	c2 = Bgetc(f);
+	c3 = Bgetc(f);
+	while(c1 != '\n' || c2 != '!' || c3 != '\n') {
+		c1 = c2;
+		c2 = c3;
+		c3 = Bgetc(f);
+		if(c3 == Beof)
+			goto eof;
+	}
+	import1 = Boffset(f);
+
+	Bseek(f, import0, 0);
+	// TODO(kaib): add in this go specific extension
+// 	ldpkg(f, import1 - import0 - 2, pn);	// -2 for !\n
+	Bseek(f, import1, 0);
+
 newloop:
 	memset(h, 0, sizeof(h));
 	version++;
@@ -1509,6 +1558,18 @@ puntfp(Prog *p)
 	// print("%s: generating ARM code (contains floating point ops %d)\n", curtext->from.sym->name, p->line);
 }
 
+Prog*
+appendp(Prog *q)
+{
+	Prog *p;
+
+	p = prg();
+	p->link = q->link;
+	q->link = p;
+	p->line = q->line;
+	return p;
+}
+
 void
 undefsym(Sym *s)
 {
diff --git a/src/cmd/5l/optab.c b/src/cmd/5l/optab.c
index b041e323427..3d7015d14c7 100644
--- a/src/cmd/5l/optab.c
+++ b/src/cmd/5l/optab.c
@@ -33,7 +33,7 @@
 Optab	optab[] =
 {
 	/* Data layout:
-	  OPCODE,	ARG0, ARG1, ARG2,		 magic numbers? */
+	  OPCODE,	from, prog->reg, to,		 magic numbers? */
 	{ ATEXT,	C_LEXT,	C_NONE,	C_LCON, 	 0, 0, 0 },
 	{ ATEXT,	C_LEXT,	C_REG,	C_LCON, 	 0, 0, 0 },
 	{ ATEXT,	C_ADDR,	C_NONE,	C_LCON, 	 0, 0, 0 },