diff -Naur gcc-11.2.0-orig/config.sub gcc-11.2.0/config.sub
--- gcc-11.2.0-orig/config.sub	2021-07-28 08:55:06.620278039 +0200
+++ gcc-11.2.0/config.sub	2021-09-17 23:35:01.028076318 +0200
@@ -1725,6 +1725,7 @@
 	     | skyos* | haiku* | rdos* | toppers* | drops* | es* \
 	     | onefs* | tirtos* | phoenix* | fuchsia* | redox* | bme* \
 	     | midnightbsd* | amdhsa* | unleashed* | emscripten* | wasi* \
+         | karlos* \
 	     | nsk* | powerunix* | genode* | zvmoe* | qnx* | emx*)
 		;;
 	# This one is extra strict with allowed versions
diff -Naur gcc-11.2.0-orig/fixincludes/mkfixinc.sh gcc-11.2.0/fixincludes/mkfixinc.sh
--- gcc-11.2.0-orig/fixincludes/mkfixinc.sh	2021-07-28 08:55:06.644278372 +0200
+++ gcc-11.2.0/fixincludes/mkfixinc.sh	2021-09-17 23:56:39.729512958 +0200
@@ -20,6 +20,7 @@
     powerpcle-*-eabisim* | \
     powerpcle-*-eabi* | \
     *-*-vxworks7* | \
+    *-*-karlos* | \
     *-musl* )
 	#  IF there is no include fixing,
 	#  THEN create a no-op fixer and exit
diff -Naur gcc-11.2.0-orig/gcc/config/karlos.h gcc-11.2.0/gcc/config/karlos.h
--- gcc-11.2.0-orig/gcc/config/karlos.h	1970-01-01 01:00:00.000000000 +0100
+++ gcc-11.2.0/gcc/config/karlos.h	2021-09-17 23:59:55.059154015 +0200
@@ -0,0 +1,24 @@
+#undef TARGET_KARLOS
+#define TARGET_KARLOS 1
+ 
+#undef LIB_SPEC
+#define LIB_SPEC "-lc"
+ 
+#undef STARTFILE_SPEC
+#define STARTFILE_SPEC "crt0.o%s crti.o%s crtbegin.o%s"
+ 
+#undef ENDFILE_SPEC
+#define ENDFILE_SPEC "crtend.o%s crtn.o%s"
+
+#undef STANDARD_STARTFILE_PREFIX
+#define STANDARD_STARTFILE_PREFIX "/lib/"
+ 
+#undef TARGET_OS_CPP_BUILTINS
+#define TARGET_OS_CPP_BUILTINS()       \
+  do {                                 \
+    builtin_define ("__karlos__");     \
+    builtin_define ("__unix__");       \
+    builtin_assert ("system=karlos");  \
+    builtin_assert ("system=unix");    \
+    builtin_assert ("system=posix");   \
+  } while(0);
diff -Naur gcc-11.2.0-orig/gcc/config/i386/t-karlos gcc-11.2.0/gcc/config/i386/t-karlos
--- gcc-11.2.0-orig/gcc/config/i386/t-karlos	1970-01-01 01:00:00.000000000 +0100
+++ gcc-11.2.0/gcc/config/i386/t-karlos	2021-09-18 00:10:44.930613877 +0200
@@ -0,0 +1,2 @@
+MULTILIB_OPTIONS += mno-red-zone
+MULTILIB_DIRNAMES += no-red-zone
diff -Naur gcc-11.2.0-orig/gcc/config.gcc gcc-11.2.0/gcc/config.gcc
--- gcc-11.2.0-orig/gcc/config.gcc	2021-07-28 08:55:07.000283339 +0200
+++ gcc-11.2.0/gcc/config.gcc	2021-09-18 00:59:44.265308559 +0200
@@ -686,6 +686,13 @@
 
 # Common parts for widely ported systems.
 case ${target} in
+*-*-karlos*)
+  gas=yes
+  gnu_ld=yes
+  default_use_cxa_exit=yes
+  use_gcc_stdint="provide"
+  native_system_header_dir="/include"
+  ;;
 *-*-darwin*)
   tmake_file="t-darwin "
   tm_file="${tm_file} darwin.h"
@@ -1909,6 +1916,10 @@
     tm_file="${tm_file} i386/unix.h i386/att.h dbxelf.h elfos.h newlib-stdint.h i386/i386elf.h i386/x86-64.h i386/rdos.h i386/rdos64.h"
     tmake_file="i386/t-i386elf t-svr4"
     ;;
+x86_64-*-karlos*)
+    tm_file="${tm_file} i386/unix.h i386/att.h dbxelf.h elfos.h glibc-stdint.h i386/i386elf.h i386/x86-64.h karlos.h"
+    tmake_file="${tmake_file} i386/t-karlos"
+    ;;
 i[34567]86-*-dragonfly*)
 	tm_file="${tm_file} i386/unix.h i386/att.h dbxelf.h elfos.h dragonfly.h dragonfly-stdint.h i386/dragonfly.h"
 	tmake_file="${tmake_file} i386/t-crtstuff"
diff -Naur gcc-11.2.0-orig/libgcc/config.host gcc-11.2.0/libgcc/config.host
--- gcc-11.2.0-orig/libgcc/config.host	2021-07-28 08:55:08.752307785 +0200
+++ gcc-11.2.0/libgcc/config.host	2021-09-18 01:01:00.231946788 +0200
@@ -676,6 +676,10 @@
 hppa*-*-netbsd*)
 	tmake_file="$tmake_file pa/t-netbsd"
 	;;
+x86_64-*-karlos*)
+    tmake_file="$tmake_file i386/t-crtstuff t-crtstuff-pic t-libgcc-pic"
+    extra_parts="$extra_parts crti.o crtbegin.o crtend.o crtn.o"
+    ;;
 i[34567]86-*-darwin*)
 	tmake_file="$tmake_file i386/t-crtpc t-crtfm i386/t-msabi"
 	tm_file="$tm_file i386/darwin-lib.h"
diff -Naur gcc-11.2.0-orig/libgcc/libgcov.h gcc-11.2.0/libgcc/libgcov.h
--- gcc-11.2.0-orig/libgcc/libgcov.h	2021-07-28 08:55:08.812308622 +0200
+++ gcc-11.2.0/libgcc/libgcov.h	2021-09-18 01:33:51.204505811 +0200
@@ -183,6 +183,11 @@
 #endif
 
 #include "gcov-io.h"
+/* NOTE(Thomas Oltmann): I have no idea why stdint isn't included by
+ * default, and I suspect this modification isn't the right way to go
+ * about this. But still, managarm gets away with the same solution,
+ * so it's probably alright. */
+#include <stdint.h>
 
 /* Structures embedded in coveraged program.  The structures generated
    by write_profile must match these.  */