diff --git a/creduce/CMakeLists.txt b/creduce/CMakeLists.txt
index 7ada4459..05da8e57 100644
--- a/creduce/CMakeLists.txt
+++ b/creduce/CMakeLists.txt
@@ -263,6 +263,9 @@ add_custom_target(Modules ALL
   COMMAND ${CMAKE_COMMAND} -E copy_if_different
     ${PROJECT_SOURCE_DIR}/pass_comments.pm
     ${PROJECT_BINARY_DIR}
+  COMMAND ${CMAKE_COMMAND} -E copy_if_different
+    ${PROJECT_SOURCE_DIR}/pass_defines.pm
+    ${PROJECT_BINARY_DIR}
   COMMAND ${CMAKE_COMMAND} -E copy_if_different
     ${PROJECT_SOURCE_DIR}/pass_include_includes.pm
     ${PROJECT_BINARY_DIR}
diff --git a/creduce/Makefile.am b/creduce/Makefile.am
index d845bfa1..ab94245b 100644
--- a/creduce/Makefile.am
+++ b/creduce/Makefile.am
@@ -24,6 +24,7 @@ dist_perllib_DATA = \
 	pass_clang_binsrch.pm \
 	pass_clex.pm \
 	pass_comments.pm \
+	pass_defines.pm \
 	pass_include_includes.pm \
 	pass_includes.pm \
 	pass_indent.pm \
diff --git a/creduce/Makefile.in b/creduce/Makefile.in
index a6002464..370a7497 100644
--- a/creduce/Makefile.in
+++ b/creduce/Makefile.in
@@ -315,6 +315,7 @@ dist_perllib_DATA = \
 	pass_clang_binsrch.pm \
 	pass_clex.pm \
 	pass_comments.pm \
+	pass_defines.pm \
 	pass_include_includes.pm \
 	pass_includes.pm \
 	pass_indent.pm \
diff --git a/creduce/creduce.in b/creduce/creduce.in
index ee86f24d..3da3831a 100644
--- a/creduce/creduce.in
+++ b/creduce/creduce.in
@@ -755,8 +755,9 @@ my @all_methods = (
 
     { "name" => "pass_include_includes", "arg" => "0",               "pri" => 100, },
     { "name" => "pass_includes", "arg" => "0",                                      "first_pass_pri" =>  0, },
-    { "name" => "pass_unifdef",  "arg" => "0",                       "pri" => 450,  "first_pass_pri" =>  0, },
-    { "name" => "pass_comments", "arg" => "0",                       "pri" => 451,  "first_pass_pri" =>  0, },
+    { "name" => "pass_defines",  "arg" => "0",                       "pri" => 450,  "first_pass_pri" =>  0, },
+    { "name" => "pass_unifdef",  "arg" => "0",                       "pri" => 451,  "first_pass_pri" =>  0, },
+    { "name" => "pass_comments", "arg" => "0",                       "pri" => 452,  "first_pass_pri" =>  0, },
     { "name" => "pass_blank",    "arg" => "0",                                      "first_pass_pri" =>  1, },
     { "name" => "pass_clang_binsrch",    "arg" => "replace-function-def-with-decl", "first_pass_pri" =>  2, },
     { "name" => "pass_clang_binsrch",    "arg" => "remove-unused-function",         "first_pass_pri" =>  3, },
diff --git a/creduce/pass_defines.pm b/creduce/pass_defines.pm
new file mode 100644
index 00000000..f3095645
--- /dev/null
+++ b/creduce/pass_defines.pm
@@ -0,0 +1,146 @@
+## -*- mode: Perl -*-
+##
+## Copyright (c) 2016 The University of Utah
+## Copyright (c) 2016 Ori Brostovski <ori@ceemple.com>, <oribrost@gmail.com>
+## Copyright (c) 2016 Ceemple Software Ltd
+##
+## All rights reserved.
+##
+## This file is distributed under the University of Illinois Open Source
+## License.  See the file COPYING for details.
+
+###############################################################################
+# test run with:  creduce --no-cache --n 1 --no-default-passes --add-pass pass_defines 0 0 `which true` bubu
+
+package pass_defines;
+
+use strict;
+use warnings;
+
+use File::Compare;
+use creduce_utils;
+
+my $missing_env_warn = 0;
+
+sub backslash_x ($) { 
+    return sprintf("\\x%X", ord($_[0])); 
+}
+
+sub check_prereqs () {
+    return 1;
+}
+
+sub new ($$) {
+    my $flag = 0;
+    return \$flag;
+}
+
+sub advance ($$$) {
+    (my $cfile, my $arg, my $state) = @_;
+    my $flag = ${$state};
+    $flag = 1;
+    return \$flag;
+}
+
+sub advance_on_success ($$$) {
+    (my $cfile, my $arg, my $state) = @_;
+    return $state;    
+}
+sub addI ($) { 
+    return "-I" . $_[0]; 
+};
+
+sub do_transform ($) {
+    (my $cfile) = @_;
+    my $suffix = substr($cfile,rindex($cfile,"."));
+
+    open INF, "<$cfile" or die;
+    my $tmpfile1 = File::Temp::tmpnam() . $suffix;
+    open TF1, ">$tmpfile1" or die;
+    my $tmpfile2 = File::Temp::tmpnam() . $suffix;
+    my $tmpfile3 = File::Temp::tmpnam() . $suffix;
+    my $index = 0;
+    
+    while (my $line = <INF>) {
+        if ($line =~ m/^\s*#\s*include/) {
+            my $sline = $line;
+            $sline =~ s/([^a-zA-Z0-9])/backslash_x($1)/ge;
+            print TF1 "char *__creduce_before_include_" . $index . " = \"$sline\";\n";
+            print TF1 $line;
+            print TF1 "char *__creduce_after_include_" . $index . " = \"$sline\";\n";
+        } else {
+            print TF1 $line;
+        }
+    }
+    close TF1;
+    close INF;
+    
+    my $iargs = "";
+    if (exists $ENV{CREDUCE_INCLUDE_PATH}) {
+        my @args = split(/:/,$ENV{CREDUCE_INCLUDE_PATH});
+        $iargs = "";
+        foreach my $iarg (@args) {
+            $iargs = $iargs . " -I" . $iarg;
+        }
+    }
+    my $lang_arg = "";
+    if (exists $ENV{CREDUCE_LANG}) {
+        if ($ENV{CREDUCE_LANG} eq "CXX") {
+            $lang_arg = "-x c++";
+        } elsif ($ENV{CREDUCE_LANG} eq "C") {
+            $lang_arg = "-x c"
+        }
+    }
+    system("clang -Wno-pragma-system-header-outside-header -E $lang_arg " .
+           "$iargs $tmpfile1 -o $tmpfile2");
+
+    unless (open TF2, "<$tmpfile2") {
+        return 0;
+    }
+    open OUTF, ">$tmpfile3" or die;
+    my $in_include = 0;
+    while (my $line = <TF2>) {
+        if ($in_include) {
+            if ($line =~ m/^char \*__creduce_after_include/) {
+                $in_include = 0;
+            }
+        } else {
+            if ($line =~ m/^char \*__creduce_before_include.*= \"(.*)\"/) {
+                my $value = $1;
+                $value =~ s/\\xA$/\n/;
+                $value =~ s/\\x(..)/chr(hex($1))/ge;
+                print OUTF $value;
+                $in_include = 1;
+            } elsif ($line !~ /^# /) {
+                print OUTF $line;
+            }
+        }
+    }
+    close OUTF;
+    close TF2;
+
+    unlink $tmpfile1;
+    unlink $tmpfile2;
+
+    if (compare($tmpfile3, $cfile)) {
+        File::Copy::move($tmpfile3, $cfile);
+        return 1;
+    } else {
+        unlink $tmpfile3;
+        return 0;
+    }
+}
+
+sub transform($$$) {
+    (my $cfile, my $arg, my $state) = @_;
+    my $flag = ${$state};
+
+    if ($flag) {
+        return ($STOP, \$flag);
+    }
+    
+    my $success = do_transform($cfile);
+    return ($success ? $OK : $STOP, \$flag);
+}
+
+1;