diff --git guix-1.5.0/gnu/packages/commencement.scm guix-1.5.0/gnu/packages/commencement.scm
index 852fa2d..2dfb6a3 100644
--- guix-1.5.0/gnu/packages/commencement.scm
+++ guix-1.5.0/gnu/packages/commencement.scm
@@ -1225,21 +1225,43 @@ ac_cv_c_float_format='IEEE (little-endian)'
     ("libc" ,glibc-mesboot0)
     ,@(alist-delete "gcc" (%boot-mesboot-core-inputs))))
 
-(define binutils-mesboot1
+(define (mesboot0-package name inputs pkg)
   (package
-    (inherit binutils-mesboot0)
-    (name "binutils-mesboot1")
-    (native-inputs (%boot-mesboot0-inputs))
+    (inherit pkg)
+    (name name)
+    (source (bootstrap-origin (package-source pkg)))
+    (native-inputs (inputs))
+    (supported-systems '("i686-linux"))
+    (inputs '())
+    (propagated-inputs '())
     (arguments
-     (substitute-keyword-arguments (package-arguments binutils-mesboot0)
-       ((#:configure-flags configure-flags)
-        #~(let ((out (assoc-ref %outputs "out")))
-            `("--disable-nls" "--disable-shared"
-              "--disable-werror"
-              "--build=i686-unknown-linux-gnu"
-              "--host=i686-unknown-linux-gnu"
-              "--with-sysroot=/"
-              ,(string-append "--prefix=" out))))))))
+     (ensure-keyword-arguments (package-arguments pkg)
+                               `(#:implicit-inputs? #f
+                                 #:guile ,%bootstrap-guile
+                                 #:tests? #f)))))
+
+;; Build native versions of critical utilities earlier, for performance reasons
+;; It would be great to build xz here, but it requres a newer gcc...
+
+;; Bash provides built-in "test", avoiding guile startup overhead
+(define bash-mesboot0
+  (let ((pkg (mesboot0-package
+   "bash-mesboot0"
+   %boot-mesboot0-inputs
+   static-bash)))
+   (package
+     (inherit pkg)
+     (arguments (substitute-keyword-arguments (package-arguments pkg)
+                   ((#:configure-flags flags)
+                    #~(cons* "CFLAGS=-g -O2" "LIBS=-lc -lnss_files -lnss_dns -lresolv"
+                       (delete
+                        "CFLAGS=-g -O2 -Wno-error=implicit-function-declaration"
+                        #$flags))))))))
+
+(define (%boot-mesboot0-native0-inputs)
+  `(("bash" ,bash-mesboot0)
+    ,@(fold alist-delete (%boot-mesboot0-inputs)
+            '("bash"))))
 
 (define gnu-make-mesboot
   (package
@@ -1253,7 +1275,7 @@ ac_cv_c_float_format='IEEE (little-endian)'
               (sha256
                (base32
                 "1rs2f9hmvy3q6zkl15jnlmnpgffm0bhw5ax0h5c7q604wqrip69x"))))
-    (native-inputs (%boot-mesboot0-inputs))
+    (native-inputs (%boot-mesboot0-native0-inputs))
     (supported-systems '("i686-linux" "x86_64-linux"))
     (inputs '())
     (propagated-inputs '())
@@ -1273,11 +1295,31 @@ ac_cv_c_float_format='IEEE (little-endian)'
                     (bin (string-append out "/bin")))
                (install-file "make" bin)))))))))
 
+(define (%boot-mesboot0-native-inputs)
+  `(("make" ,gnu-make-mesboot)
+    ,@(fold alist-delete (%boot-mesboot0-native0-inputs)
+            '("make"))))
+
+(define binutils-mesboot1
+  (package
+    (inherit binutils-mesboot0)
+    (name "binutils-mesboot1")
+    (native-inputs (%boot-mesboot0-native-inputs))
+    (arguments
+     (substitute-keyword-arguments (package-arguments binutils-mesboot0)
+       ((#:configure-flags configure-flags)
+        #~(let ((out (assoc-ref %outputs "out")))
+            `("--disable-nls" "--disable-shared"
+              "--disable-werror"
+              "--build=i686-unknown-linux-gnu"
+              "--host=i686-unknown-linux-gnu"
+              "--with-sysroot=/"
+              ,(string-append "--prefix=" out))))))))
+
 (define (%boot-mesboot1-inputs)
   `(("binutils" ,binutils-mesboot1)
-    ("make" ,gnu-make-mesboot)
-    ,@(fold alist-delete (%boot-mesboot0-inputs)
-            '("binutils" "make"))))
+    ,@(fold alist-delete (%boot-mesboot0-native-inputs)
+            '("binutils"))))
 
 (define gmp-boot
   (let ((version "4.3.2"))
@@ -1467,7 +1509,7 @@ ac_cv_c_float_format='IEEE (little-endian)'
                 ;; libstdc++ is being compiled.
                 (setenv "CPLUS_INCLUDE_PATH" (getenv "C_INCLUDE_PATH"))))))))))
 
-(define (%boot-mesboot2-inputs)
+(define (%boot-mesboot2-bootar-inputs)
   `(("gcc" ,gcc-mesboot1)
     ,@(alist-delete "gcc" (%boot-mesboot1-inputs))))
 
@@ -1490,7 +1532,7 @@ ac_cv_c_float_format='IEEE (little-endian)'
     (supported-systems '("i686-linux" "x86_64-linux"))
     (inputs '())
     (propagated-inputs '())
-    (native-inputs (%boot-mesboot2-inputs))
+    (native-inputs (%boot-mesboot2-bootar-inputs))
     (arguments
      `(#:implicit-inputs? #f
        #:guile ,%bootstrap-guile
@@ -1504,6 +1546,119 @@ ac_cv_c_float_format='IEEE (little-endian)'
            (lambda _
              (invoke "./hello"))))))))
 
+;; Now, that we have GCC 4.6, we can finally build xz.
+(define xz-mesboot0
+  (let ((pkg (mesboot0-package "xz-mesboot0" %boot-mesboot2-bootar-inputs xz)))
+    (package
+      (inherit pkg)
+      (arguments
+       (ensure-keyword-arguments (package-arguments pkg)
+                                 ;; XXX: This fails even though the
+                                 ;; actual runpaths seem fine.
+                                 `(#:validate-runpath? #f
+                                 ;; XXX: The build gets stuck
+                                 ;; when parallel build is enabled.
+                                   #:parallel-build? #f
+                                   #:configure-flags (list
+                                                      ;; static build
+                                                      "--enable-static"
+                                                      "--disable-shared"
+                                                      ;; missing pthread.h
+                                                      "--enable-threads=no"
+                                                      ;; extern inlines broken
+                                                      "CFLAGS=-g -O2 -fgnu89-inline")))))))
+
+;; Tar doesn't build at this stage, so teach gash-utils tar to use xz using a wrapper
+(define gash-utils-tar-wrapper
+  ;; Wrapper around gash-utils tar that extracts xz files using xz-mesboot0
+  ;; before passing them on to tar.
+  (package
+    (inherit gash-utils-boot)
+    (name "gash-utils-tar-wrapper")
+    (source #f)
+    (inputs '())
+    (native-inputs `(("bash" ,bash-mesboot0)
+                     ("coreutils" ,gash-utils-boot)
+                     ("gzip" ,gzip-mesboot)
+                     ("xz" ,xz-mesboot0)))
+    (arguments
+     `(#:implicit-inputs? #f
+       #:guile ,%bootstrap-guile
+       #:phases
+       (modify-phases %standard-phases
+         (delete 'unpack)
+         (delete 'configure)
+         (delete 'install)
+         (replace 'build
+           (lambda* (#:key outputs #:allow-other-keys)
+             (let* ((out (assoc-ref outputs "out"))
+                    (bash (assoc-ref %build-inputs "bash"))
+                    (coreutils (assoc-ref %build-inputs "coreutils"))
+                    (xz (assoc-ref %build-inputs "xz"))
+                    (gzip (assoc-ref %build-inputs "gzip"))
+                    (bin (string-append out "/bin")))
+               (mkdir-p bin)
+               (for-each
+                (lambda (program)
+                  (let ((wrapper (string-append bin "/" program)))
+                    (with-output-to-file wrapper
+                      (lambda _
+                        (display (string-append "#!" bash "/bin/bash
+
+# Check if file is GZIP or XZ compressed
+if [[ \"$#\" -eq 2 && \"$1\" = xvf && \"$2\" = *.tar.xz ]]; then
+    # Decompress using xz to temporary file
+    if ! " xz "/bin/xz -dc -- \"$2\" > /tmp/tar_wrapper.tar; then
+        echo \"Error: failed to decompress $2\" >&2
+        rm -f /tmp/tar_wrapper.tar
+        exit 1
+    fi
+
+    # Extract using gash-utils tar
+    " coreutils "/bin/tar \"$1\" /tmp/tar_wrapper.tar
+    status=$?
+
+    # Clean up
+    rm -f /tmp/tar_wrapper.tar
+
+    exit $status
+elif [[ \"$#\" -eq 2 && \"$1\" = xvf && \"$2\" = *.tar.gz ]]; then
+    # Decompress using gzip to temporary file
+    if ! " gzip "/bin/gzip -dc \"$2\" > /tmp/tar_wrapper.tar; then
+        echo \"Error: failed to decompress $2\" >&2
+        rm -f /tmp/tar_wrapper.tar
+        exit 1
+    fi
+
+    # Extract using gash-utils tar
+    " coreutils "/bin/tar \"$1\" /tmp/tar_wrapper.tar
+    status=$?
+
+    # Clean up
+    rm -f /tmp/tar_wrapper.tar
+
+    exit $status
+else
+    # Fall back to direct gash-utils tar call
+    exec " coreutils "/bin/tar \"$@\"
+fi
+"))
+                        (chmod wrapper #o555)))))
+                '("tar")))))
+         (replace 'check
+           (lambda* (#:key outputs #:allow-other-keys)
+             (let* ((bash (assoc-ref %build-inputs "bash"))
+                    (bin (string-append bash "/bin"))
+                    (program (string-append bin "/bash")))
+               (invoke program "--help")))))))))
+
+(define (%boot-mesboot2-inputs)
+  `(("xz" ,xz-mesboot0)
+    ("tar" ,gash-utils-tar-wrapper)
+    ;; we can drop bootar here; gzip + xz + gash-utils tar is enough to proceed
+    ,@(fold alist-delete (%boot-mesboot2-bootar-inputs)
+            '("bootar"))))
+
 (define binutils-mesboot
   (package
     (inherit binutils-mesboot1)
@@ -1709,7 +1864,7 @@ SHELL := " shell "
     (name "gcc-mesboot1-wrapper")
     (source #f)
     (inputs '())
-    (native-inputs `(("bash" ,gash-boot)
+    (native-inputs `(("bash" ,bash-mesboot0)
                      ("coreutils" ,gash-utils-boot)
                      ("libc" ,glibc-mesboot)
                      ("gcc" ,gcc-mesboot1)))
@@ -1848,7 +2003,7 @@ exec " gcc "/bin/" program
     (version (package-version gcc-mesboot))
     (source #f)
     (inputs '())
-    (native-inputs `(("bash" ,gash-boot)
+    (native-inputs `(("bash" ,bash-mesboot0)
                      ("coreutils" ,gash-utils-boot)
                      ("libc" ,glibc-mesboot)
                      ("gcc" ,gcc-mesboot)))))
@@ -1966,7 +2121,7 @@ exec " gcc "/bin/" program
     ("tar" ,tar-mesboot)
     ("xz" ,xz-mesboot)
     ,@(fold alist-delete (%boot-mesboot5-inputs)
-            '("bash" "coreutils" "bootar" "kernel-headers"))))
+            '("bash" "coreutils" "tar" "kernel-headers"))))
 
 (define (%bootstrap-inputs+toolchain)
   ;; The traditional bootstrap-inputs.  For the i686-linux, x86_64-linux