diff --git a/mach/i386/ncg/mach.c b/mach/i386/ncg/mach.c
index 6b08565d8..3388c6696 100644
--- a/mach/i386/ncg/mach.c
+++ b/mach/i386/ncg/mach.c
@@ -158,6 +158,21 @@ regreturn()
 }
 #endif /* REGVARS */
 
+#ifdef MACH_OPTIONS
+static int gdb_flag = 0;
+
+mach_option(s)
+	char *s;
+{
+	if (! strcmp(s, "-gdb")) {
+		gdb_flag = 1;
+	}
+	else {
+		error("Unknown flag %s", s);
+	}
+}
+#endif /* MACH_OPTIONS */
+
 mes(type) word type ; {
 	int argt, a1, a2 ;
 
@@ -186,6 +201,16 @@ mes(type) word type ; {
 		argt = getarg(cst_ptyp);
 		a2 = argval;
 		argt = getarg(cst_ptyp|nof_ptyp|sof_ptyp|ilb_ptyp|pro_ptyp);
+#ifdef MACH_OPTIONS
+		if (gdb_flag) {
+			if (a1 == N_PSYM) {
+				/* Change offset from AB into offset from
+				   the frame pointer (bp).
+				*/
+				argval += 8;
+			}
+		}
+#endif
 		fprintf(codefile, "%s, 0x%x, %d\n", strarg(argt), a1, a2);
 		argt = getarg(end_ptyp);
 		break;
@@ -197,7 +222,11 @@ mes(type) word type ; {
 			argt = getarg(cst_ptyp);
 		}
 		swtxt();
-		if (argval == N_SLINE) {
+		if (argval == N_SLINE
+#ifdef MACH_OPTIONS
+		    && ! gdb_flag
+#endif
+		) {
 			fputs("call ___u_LiB\n", codefile);
 			cleanregs();	/* debugger might change variables */
 		}
diff --git a/mach/i386/ncg/mach.h b/mach/i386/ncg/mach.h
index 62c007e4c..40c9c6321 100644
--- a/mach/i386/ncg/mach.h
+++ b/mach/i386/ncg/mach.h
@@ -31,3 +31,4 @@
 #define fmt_id(fr,to)	sprintf(to, "_%s", fr)
 
 #define BSS_INIT        0
+#define MACH_OPTIONS
diff --git a/mach/m68020/ncg/mach.c b/mach/m68020/ncg/mach.c
index 5651cac4f..a7eb6ebf3 100644
--- a/mach/m68020/ncg/mach.c
+++ b/mach/m68020/ncg/mach.c
@@ -178,7 +178,20 @@ prolog(n) full n; {
 	nlocals = n;
 }
 
+#ifdef MACH_OPTIONS
+static int gdb_flag = 0;
 
+mach_option(s)
+	char *s;
+{
+	if (! strcmp(s, "-gdb")) {
+		gdb_flag = 1;
+	}
+	else {
+		error("Unknown flag %s", s);
+	}
+}
+#endif /* MACH_OPTIONS */
 
 mes(type) word type ; {
 	int argt, a1, a2 ;
@@ -208,9 +221,14 @@ mes(type) word type ; {
 		argt = getarg(cst_ptyp);
 		a2 = argval;
 		argt = getarg(cst_ptyp|nof_ptyp|sof_ptyp|ilb_ptyp|pro_ptyp);
-#ifdef DBX
-		if (a1 == N_PSYM) {
-			argval += 8;
+#ifdef MACH_OPTIONS
+		if (gdb_flag) {
+			if (a1 == N_PSYM) {
+				/* Change offset from AB into offset from
+				   the frame pointer.
+				*/
+				argval += 8;
+			}
 		}
 #endif
 		fprintf(codefile, "%s, 0x%x, %d\n", strarg(argt), a1, a2);
@@ -224,8 +242,11 @@ mes(type) word type ; {
 			argt = getarg(cst_ptyp);
 		}
 		swtxt();
-#ifndef DBX
-		if (argval == N_SLINE) {
+		if (argval == N_SLINE
+#ifdef MACH_OPTIONS
+		    && ! gdb_flag
+#endif
+		) {
 #ifdef TBL68020
 			fputs("jsr (___u_LiB)\n", codefile);
 #else
@@ -233,7 +254,6 @@ mes(type) word type ; {
 #endif
 			cleanregs();	/* debugger might change variables */
 		}
-#endif
 		fprintf(codefile, ".symd \"%s\", 0x%x,", str, (int) argval);
 		argt = getarg(cst_ptyp);
 		fprintf(codefile, "%d\n", (int) argval);
diff --git a/mach/m68020/ncg/mach.h b/mach/m68020/ncg/mach.h
index c9c975a3e..c78d0873e 100644
--- a/mach/m68020/ncg/mach.h
+++ b/mach/m68020/ncg/mach.h
@@ -46,3 +46,4 @@ You must specify the appropriate word size, then REMOVE tables.c
 #define fmt_id(sf,st)	sprintf(st,"_%s",sf)
 
 #define BSS_INIT	0
+#define MACH_OPTIONS
diff --git a/mach/m68k2/ncg/mach.c b/mach/m68k2/ncg/mach.c
index 5651cac4f..a7eb6ebf3 100644
--- a/mach/m68k2/ncg/mach.c
+++ b/mach/m68k2/ncg/mach.c
@@ -178,7 +178,20 @@ prolog(n) full n; {
 	nlocals = n;
 }
 
+#ifdef MACH_OPTIONS
+static int gdb_flag = 0;
 
+mach_option(s)
+	char *s;
+{
+	if (! strcmp(s, "-gdb")) {
+		gdb_flag = 1;
+	}
+	else {
+		error("Unknown flag %s", s);
+	}
+}
+#endif /* MACH_OPTIONS */
 
 mes(type) word type ; {
 	int argt, a1, a2 ;
@@ -208,9 +221,14 @@ mes(type) word type ; {
 		argt = getarg(cst_ptyp);
 		a2 = argval;
 		argt = getarg(cst_ptyp|nof_ptyp|sof_ptyp|ilb_ptyp|pro_ptyp);
-#ifdef DBX
-		if (a1 == N_PSYM) {
-			argval += 8;
+#ifdef MACH_OPTIONS
+		if (gdb_flag) {
+			if (a1 == N_PSYM) {
+				/* Change offset from AB into offset from
+				   the frame pointer.
+				*/
+				argval += 8;
+			}
 		}
 #endif
 		fprintf(codefile, "%s, 0x%x, %d\n", strarg(argt), a1, a2);
@@ -224,8 +242,11 @@ mes(type) word type ; {
 			argt = getarg(cst_ptyp);
 		}
 		swtxt();
-#ifndef DBX
-		if (argval == N_SLINE) {
+		if (argval == N_SLINE
+#ifdef MACH_OPTIONS
+		    && ! gdb_flag
+#endif
+		) {
 #ifdef TBL68020
 			fputs("jsr (___u_LiB)\n", codefile);
 #else
@@ -233,7 +254,6 @@ mes(type) word type ; {
 #endif
 			cleanregs();	/* debugger might change variables */
 		}
-#endif
 		fprintf(codefile, ".symd \"%s\", 0x%x,", str, (int) argval);
 		argt = getarg(cst_ptyp);
 		fprintf(codefile, "%d\n", (int) argval);
diff --git a/mach/m68k2/ncg/mach.h b/mach/m68k2/ncg/mach.h
index c9c975a3e..c78d0873e 100644
--- a/mach/m68k2/ncg/mach.h
+++ b/mach/m68k2/ncg/mach.h
@@ -46,3 +46,4 @@ You must specify the appropriate word size, then REMOVE tables.c
 #define fmt_id(sf,st)	sprintf(st,"_%s",sf)
 
 #define BSS_INIT	0
+#define MACH_OPTIONS
diff --git a/mach/m68k4/ncg/mach.c b/mach/m68k4/ncg/mach.c
index 5651cac4f..a7eb6ebf3 100644
--- a/mach/m68k4/ncg/mach.c
+++ b/mach/m68k4/ncg/mach.c
@@ -178,7 +178,20 @@ prolog(n) full n; {
 	nlocals = n;
 }
 
+#ifdef MACH_OPTIONS
+static int gdb_flag = 0;
 
+mach_option(s)
+	char *s;
+{
+	if (! strcmp(s, "-gdb")) {
+		gdb_flag = 1;
+	}
+	else {
+		error("Unknown flag %s", s);
+	}
+}
+#endif /* MACH_OPTIONS */
 
 mes(type) word type ; {
 	int argt, a1, a2 ;
@@ -208,9 +221,14 @@ mes(type) word type ; {
 		argt = getarg(cst_ptyp);
 		a2 = argval;
 		argt = getarg(cst_ptyp|nof_ptyp|sof_ptyp|ilb_ptyp|pro_ptyp);
-#ifdef DBX
-		if (a1 == N_PSYM) {
-			argval += 8;
+#ifdef MACH_OPTIONS
+		if (gdb_flag) {
+			if (a1 == N_PSYM) {
+				/* Change offset from AB into offset from
+				   the frame pointer.
+				*/
+				argval += 8;
+			}
 		}
 #endif
 		fprintf(codefile, "%s, 0x%x, %d\n", strarg(argt), a1, a2);
@@ -224,8 +242,11 @@ mes(type) word type ; {
 			argt = getarg(cst_ptyp);
 		}
 		swtxt();
-#ifndef DBX
-		if (argval == N_SLINE) {
+		if (argval == N_SLINE
+#ifdef MACH_OPTIONS
+		    && ! gdb_flag
+#endif
+		) {
 #ifdef TBL68020
 			fputs("jsr (___u_LiB)\n", codefile);
 #else
@@ -233,7 +254,6 @@ mes(type) word type ; {
 #endif
 			cleanregs();	/* debugger might change variables */
 		}
-#endif
 		fprintf(codefile, ".symd \"%s\", 0x%x,", str, (int) argval);
 		argt = getarg(cst_ptyp);
 		fprintf(codefile, "%d\n", (int) argval);
diff --git a/mach/m68k4/ncg/mach.h b/mach/m68k4/ncg/mach.h
index c9c975a3e..c78d0873e 100644
--- a/mach/m68k4/ncg/mach.h
+++ b/mach/m68k4/ncg/mach.h
@@ -46,3 +46,4 @@ You must specify the appropriate word size, then REMOVE tables.c
 #define fmt_id(sf,st)	sprintf(st,"_%s",sf)
 
 #define BSS_INIT	0
+#define MACH_OPTIONS
diff --git a/mach/moon3/ncg/mach.c b/mach/moon3/ncg/mach.c
index 5651cac4f..a7eb6ebf3 100644
--- a/mach/moon3/ncg/mach.c
+++ b/mach/moon3/ncg/mach.c
@@ -178,7 +178,20 @@ prolog(n) full n; {
 	nlocals = n;
 }
 
+#ifdef MACH_OPTIONS
+static int gdb_flag = 0;
 
+mach_option(s)
+	char *s;
+{
+	if (! strcmp(s, "-gdb")) {
+		gdb_flag = 1;
+	}
+	else {
+		error("Unknown flag %s", s);
+	}
+}
+#endif /* MACH_OPTIONS */
 
 mes(type) word type ; {
 	int argt, a1, a2 ;
@@ -208,9 +221,14 @@ mes(type) word type ; {
 		argt = getarg(cst_ptyp);
 		a2 = argval;
 		argt = getarg(cst_ptyp|nof_ptyp|sof_ptyp|ilb_ptyp|pro_ptyp);
-#ifdef DBX
-		if (a1 == N_PSYM) {
-			argval += 8;
+#ifdef MACH_OPTIONS
+		if (gdb_flag) {
+			if (a1 == N_PSYM) {
+				/* Change offset from AB into offset from
+				   the frame pointer.
+				*/
+				argval += 8;
+			}
 		}
 #endif
 		fprintf(codefile, "%s, 0x%x, %d\n", strarg(argt), a1, a2);
@@ -224,8 +242,11 @@ mes(type) word type ; {
 			argt = getarg(cst_ptyp);
 		}
 		swtxt();
-#ifndef DBX
-		if (argval == N_SLINE) {
+		if (argval == N_SLINE
+#ifdef MACH_OPTIONS
+		    && ! gdb_flag
+#endif
+		) {
 #ifdef TBL68020
 			fputs("jsr (___u_LiB)\n", codefile);
 #else
@@ -233,7 +254,6 @@ mes(type) word type ; {
 #endif
 			cleanregs();	/* debugger might change variables */
 		}
-#endif
 		fprintf(codefile, ".symd \"%s\", 0x%x,", str, (int) argval);
 		argt = getarg(cst_ptyp);
 		fprintf(codefile, "%d\n", (int) argval);
diff --git a/mach/moon3/ncg/mach.h b/mach/moon3/ncg/mach.h
index c9c975a3e..c78d0873e 100644
--- a/mach/moon3/ncg/mach.h
+++ b/mach/moon3/ncg/mach.h
@@ -46,3 +46,4 @@ You must specify the appropriate word size, then REMOVE tables.c
 #define fmt_id(sf,st)	sprintf(st,"_%s",sf)
 
 #define BSS_INIT	0
+#define MACH_OPTIONS
diff --git a/mach/sparc/ce/ce.src/ms_reg.c b/mach/sparc/ce/ce.src/ms_reg.c
index 9f1e3f061..771b907ad 100644
--- a/mach/sparc/ce/ce.src/ms_reg.c
+++ b/mach/sparc/ce/ce.src/ms_reg.c
@@ -306,13 +306,17 @@ C_mes_end()
 	}
 }
 
+extern int __gdb_flag;
+
 C_cst( l)
 arith l;
 {
+	static int correct_offset;
+
 	if (db_mes) {
 		if (! db_str) {
 			switchseg( SEGTXT);
-			if (l == N_SLINE) {
+			if (l == N_SLINE && ! __gdb_flag) {
 				flush_cache();
 				fprintf(codefile, "call ___uX_LiB\nnop\n");
 			}
@@ -323,8 +327,17 @@ arith l;
 			db_str = 1;
 			db_nul = 1;
 		}
-		else	fprint(codefile, ",0x%lx", (long) l);
+		else {
+			if (correct_offset++ == -1) {
+				l += EM_BSIZE;
+			}
+			fprint(codefile, ",0x%lx", (long) l);
+		}
 		if (! db_nul) {
+			correct_offset = 0;
+			if (l == N_PSYM && __gdb_flag) {
+				correct_offset = -2;
+			}
 			fprint(codefile, ",0");
 			db_nul = 1;
 		}
diff --git a/mach/sparc/ce_cg/convert.c b/mach/sparc/ce_cg/convert.c
index 1db46e34f..07130686d 100644
--- a/mach/sparc/ce_cg/convert.c
+++ b/mach/sparc/ce_cg/convert.c
@@ -29,6 +29,7 @@ char *filename;			/* Name of input file */
 char *out_file;			/* Name of output file */
 int errors;			/* Number of errors */
 int debug;
+int __gdb_flag;
 extern char *C_error;
 
 main(argc,argv)
@@ -49,6 +50,10 @@ main(argc,argv)
 			debug= 1;
 			continue;
 		}
+		if (! strcmp(av[0], "-gdb")) {
+			__gdb_flag = 1;
+			continue;
+		}
 		if (!filename)
 		{
 			if (strcmp(*av, "-"))
diff --git a/mach/vax4/cg/mach.c b/mach/vax4/cg/mach.c
index 6edd36128..f434aaaa3 100644
--- a/mach/vax4/cg/mach.c
+++ b/mach/vax4/cg/mach.c
@@ -47,6 +47,21 @@ con_mult(sz)
 	fprintf(codefile,".data4\t%s\n",str);
 }
 
+#ifdef MACH_OPTIONS
+static int gdb_flag = 0;
+
+mach_option(s)
+	char *s;
+{
+	if (! strcmp(s, "-gdb")) {
+		gdb_flag = 1;
+	}
+	else {
+		error("Unknown flag %s", s);
+	}
+}
+#endif /* MACH_OPTIONS */
+
 mes(mesno)
 	word	mesno;
 {
@@ -77,9 +92,14 @@ mes(mesno)
 		argt = getarg(cst_ptyp);
 		a2 = argval;
 		argt = getarg(cst_ptyp|nof_ptyp|sof_ptyp|ilb_ptyp|pro_ptyp);
-#ifdef DBX
-		if (a1 == N_PSYM) {
-			argval += 4;
+#ifdef MACH_OPTIONS
+		if (gdb_flag) {
+			if (a1 == N_PSYM) {
+				/* Change offset from AB into offset from
+				   the frame pointer (ab).
+				*/
+				argval += 4;
+			}
 		}
 #endif
 		fprintf(codefile, "%s, 0x%x, %d\n", strarg(argt), a1, a2);
@@ -93,12 +113,14 @@ mes(mesno)
 			argt = getarg(cst_ptyp);
 		}
 		swtxt();
-#ifndef DBX
-		if (argval == N_SLINE) {
+		if (argval == N_SLINE
+#ifdef MACH_OPTIONS
+		    && ! gdb_flag
+#endif
+		) {
 			fputs("calls $0,___u_LiB\n", codefile);
 			cleanregs();	/* debugger might change variables */
 		}
-#endif
 		fprintf(codefile, ".symd \"%s\", 0x%x,", str, (int) argval);
 		argt = getarg(cst_ptyp);
 		fprintf(codefile, "%d\n", (int) argval);
diff --git a/mach/vax4/cg/mach.h b/mach/vax4/cg/mach.h
index 3c7442d93..fbd29a679 100644
--- a/mach/vax4/cg/mach.h
+++ b/mach/vax4/cg/mach.h
@@ -27,5 +27,6 @@
 #define con_dlb(x)	fprintf(codefile,".data4\t%s\n",x)
 
 #define BSS_INIT	0
+#define MACH_OPTIONS
 
 #define modhead		".sect .text\n.sect .rom\n.sect .data\n.sect .bss\n"