diff --git a/aclocal.m4 b/aclocal.m4
index 52445594a79c..7da646b1d114 100644
--- a/aclocal.m4
+++ b/aclocal.m4
@@ -7,14 +7,10 @@ builtin(include, build/autoconf/hooks.m4)dnl
 builtin(include, build/autoconf/config.status.m4)dnl
 builtin(include, build/autoconf/toolchain.m4)dnl
 builtin(include, build/autoconf/altoptions.m4)dnl
-builtin(include, build/autoconf/mozprog.m4)dnl
-builtin(include, build/autoconf/mozheader.m4)dnl
 builtin(include, build/autoconf/compiler-opts.m4)dnl
 builtin(include, build/autoconf/arch.m4)dnl
 builtin(include, build/autoconf/clang-plugin.m4)dnl
 
-MOZ_PROG_CHECKMSYS()
-
 # Read the user's .mozconfig script.  We can't do this in
 # configure.in: autoconf puts the argument parsing code above anything
 # expanded from configure.in, and we need to get the configure options
diff --git a/build/autoconf/mozheader.m4 b/build/autoconf/mozheader.m4
deleted file mode 100644
index e99e35a403cb..000000000000
--- a/build/autoconf/mozheader.m4
+++ /dev/null
@@ -1,32 +0,0 @@
-dnl This Source Code Form is subject to the terms of the Mozilla Public
-dnl License, v. 2.0. If a copy of the MPL was not distributed with this
-dnl file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
-dnl MOZ_CHECK_HEADER(HEADER-FILE, [ACTION-IF-FOUND [, ACTION-IF-NOT-FOUND [, INCLUDES]]])
-AC_DEFUN([MOZ_CHECK_HEADER],
-[ dnl Do the transliteration at runtime so arg 1 can be a shell variable.
-  ac_safe=`echo "$1" | sed 'y%./+-%__p_%'`
-  AC_MSG_CHECKING([for $1])
-  AC_CACHE_VAL(ac_cv_header_$ac_safe,
- [ AC_TRY_COMPILE([$4
-#include <$1>], ,
-                  eval "ac_cv_header_$ac_safe=yes",
-                  eval "ac_cv_header_$ac_safe=no") ])
-  if eval "test \"`echo '$ac_cv_header_'$ac_safe`\" = yes"; then
-    AC_MSG_RESULT(yes)
-    ifelse([$2], , :, [$2])
-  else
-    AC_MSG_RESULT(no)
-    ifelse([$3], , , [$3])
-  fi
-])
-
-dnl MOZ_CHECK_HEADERS(HEADER-FILE... [, ACTION-IF-FOUND [, ACTION-IF-NOT-FOUND [, INCLUDES]]])
-AC_DEFUN([MOZ_CHECK_HEADERS],
-[ for ac_hdr in $1
-  do
-    MOZ_CHECK_HEADER($ac_hdr,
-                     [ ac_tr_hdr=HAVE_`echo $ac_hdr | sed 'y%abcdefghijklmnopqrstuvwxyz./-%ABCDEFGHIJKLMNOPQRSTUVWXYZ___%'`
-                       AC_DEFINE_UNQUOTED($ac_tr_hdr) $2], $3, [$4])
-  done
-])
diff --git a/build/autoconf/mozprog.m4 b/build/autoconf/mozprog.m4
deleted file mode 100644
index 00e357a80790..000000000000
--- a/build/autoconf/mozprog.m4
+++ /dev/null
@@ -1,42 +0,0 @@
-dnl This Source Code Form is subject to the terms of the Mozilla Public
-dnl License, v. 2.0. If a copy of the MPL was not distributed with this
-dnl file, You can obtain one at http://mozilla.org/MPL/2.0/.
-
-AC_DEFUN([MOZ_PROG_CHECKMSYS],
-[AC_REQUIRE([AC_INIT_BINSH])dnl
-if test `uname -s | grep -c "MINGW\|MSYS" 2>/dev/null` != "0"; then
-  msyshost=1
-fi
-])
-
-AC_DEFUN([MOZ_PATH_PROG],
-[ AC_PATH_PROG($1,$2,$3,$4)
-  if test "$msyshost"; then
-    case "[$]$1" in
-    /*)
-      tmp_DIRNAME=`dirname "[$]$1"`
-      tmp_BASENAME=`basename "[$]$1"`
-      tmp_PWD=`cd "$tmp_DIRNAME" && pwd -W`
-      $1="$tmp_PWD/$tmp_BASENAME"
-      if test -e "[$]$1.exe"; then
-        $1="[$]$1.exe"
-      fi
-    esac
-  fi
-])
-
-AC_DEFUN([MOZ_PATH_PROGS],
-[  AC_PATH_PROGS($1,$2,$3,$4)
-  if test "$msyshost"; then
-    case "[$]$1" in
-    /*)
-      tmp_DIRNAME=`dirname "[$]$1"`
-      tmp_BASENAME=`basename "[$]$1"`
-      tmp_PWD=`cd "$tmp_DIRNAME" && pwd -W`
-      $1="$tmp_PWD/$tmp_BASENAME"
-      if test -e "[$]$1.exe"; then
-        $1="[$]$1.exe"
-      fi
-    esac
-  fi
-])
diff --git a/js/src/aclocal.m4 b/js/src/aclocal.m4
index a9ae04074baa..0cac85f9a48a 100644
--- a/js/src/aclocal.m4
+++ b/js/src/aclocal.m4
@@ -7,8 +7,6 @@ builtin(include, ../../build/autoconf/hooks.m4)dnl
 builtin(include, ../../build/autoconf/config.status.m4)dnl
 builtin(include, ../../build/autoconf/toolchain.m4)dnl
 builtin(include, ../../build/autoconf/altoptions.m4)dnl
-builtin(include, ../../build/autoconf/mozprog.m4)dnl
-builtin(include, ../../build/autoconf/mozheader.m4)dnl
 builtin(include, ../../build/autoconf/compiler-opts.m4)dnl
 builtin(include, ../../build/autoconf/arch.m4)dnl
 builtin(include, ../../build/autoconf/clang-plugin.m4)dnl
@@ -22,7 +20,6 @@ srcdir="$srcdir/../.."
 __MOZ_AC_INIT_PREPARE($1)
 ])
 
-MOZ_PROG_CHECKMSYS()
 dnl This won't actually read the mozconfig, but data that configure.py
 dnl will have placed for us to read. Configure.py takes care of not reading
 dnl the mozconfig where appropriate but can still give us some variables