diff --git a/Documentation/config.txt b/Documentation/config.txt
index c6f09f801a..0b53cab6af 100644
--- a/Documentation/config.txt
+++ b/Documentation/config.txt
@@ -461,6 +461,14 @@ it will be treated as a shell command.  For example, defining
 executed from the top-level directory of a repository, which may
 not necessarily be the current directory.
 
+apply.ignorewhitespace::
+	When set to 'change', tells 'git-apply' to ignore changes in
+	whitespace, in the same way as the '--ignore-space-change'
+	option.
+	When set to one of: no, none, never, false tells 'git-apply' to
+	respect all whitespace differences.
+	See linkgit:git-apply[1].
+
 apply.whitespace::
 	Tells 'git-apply' how to handle whitespaces, in the same way
 	as the '--whitespace' option. See linkgit:git-apply[1].
diff --git a/Documentation/git-am.txt b/Documentation/git-am.txt
index 32e689b2bf..fcacc94650 100644
--- a/Documentation/git-am.txt
+++ b/Documentation/git-am.txt
@@ -11,7 +11,7 @@ SYNOPSIS
 [verse]
 'git am' [--signoff] [--keep] [--utf8 | --no-utf8]
 	 [--3way] [--interactive] [--committer-date-is-author-date]
-	 [--ignore-date]
+	 [--ignore-date] [--ignore-space-change | --ignore-whitespace]
 	 [--whitespace=<option>] [-C<n>] [-p<n>] [--directory=<dir>]
 	 [--reject] [-q | --quiet]
 	 [<mbox> | <Maildir>...]
@@ -65,6 +65,9 @@ default.   You can use `--no-utf8` to override this.
 	it is supposed to apply to and we have those blobs
 	available locally.
 
+--ignore-date::
+--ignore-space-change::
+--ignore-whitespace::
 --whitespace=<option>::
 -C<n>::
 -p<n>::
diff --git a/Documentation/git-apply.txt b/Documentation/git-apply.txt
index 735374d7df..5ee8c91f2d 100644
--- a/Documentation/git-apply.txt
+++ b/Documentation/git-apply.txt
@@ -13,6 +13,7 @@ SYNOPSIS
 	  [--apply] [--no-add] [--build-fake-ancestor=<file>] [-R | --reverse]
 	  [--allow-binary-replacement | --binary] [--reject] [-z]
 	  [-pNUM] [-CNUM] [--inaccurate-eof] [--recount] [--cached]
+	  [--ignore-space-change | --ignore-whitespace ]
 	  [--whitespace=<nowarn|warn|fix|error|error-all>]
 	  [--exclude=PATH] [--include=PATH] [--directory=<root>]
 	  [--verbose] [<patch>...]
@@ -149,6 +150,14 @@ patch to each path is used.  A patch to a path that does not match any
 include/exclude pattern is used by default if there is no include pattern
 on the command line, and ignored if there is any include pattern.
 
+--ignore-space-change::
+--ignore-whitespace::
+	When applying a patch, ignore changes in whitespace in context
+	lines if necessary.
+	Context lines will preserve their whitespace, and they will not
+	undergo whitespace fixing regardless of the value of the
+	`--whitespace` option. New lines will still be fixed, though.
+
 --whitespace=<action>::
 	When applying a patch, detect a new or modified line that has
 	whitespace errors.  What are considered whitespace errors is
@@ -205,6 +214,10 @@ running `git apply --directory=modules/git-gui`.
 Configuration
 -------------
 
+apply.ignorewhitespace::
+	Set to 'change' if you want changes in whitespace to be ignored by default.
+	Set to one of: no, none, never, false if you want changes in
+	whitespace to be significant.
 apply.whitespace::
 	When no `--whitespace` flag is given from the command
 	line, this configuration item is used as the default.
diff --git a/Documentation/git-rebase.txt b/Documentation/git-rebase.txt
index db1b71d248..0aefc34d0d 100644
--- a/Documentation/git-rebase.txt
+++ b/Documentation/git-rebase.txt
@@ -268,8 +268,9 @@ OPTIONS
 	exit with the message "Current branch is up to date" in such a
 	situation.
 
+--ignore-whitespace::
 --whitespace=<option>::
-	This flag is passed to the 'git-apply' program
+	These flag are passed to the 'git-apply' program
 	(see linkgit:git-apply[1]) that applies the patch.
 	Incompatible with the --interactive option.
 
diff --git a/builtin-apply.c b/builtin-apply.c
index dc0ff5e08a..d9303578b6 100644
--- a/builtin-apply.c
+++ b/builtin-apply.c
@@ -61,6 +61,13 @@ static enum ws_error_action {
 static int whitespace_error;
 static int squelch_whitespace_errors = 5;
 static int applied_after_fixing_ws;
+
+static enum ws_ignore {
+	ignore_ws_none,
+	ignore_ws_change,
+} ws_ignore_action = ignore_ws_none;
+
+
 static const char *patch_input_file;
 static const char *root;
 static int root_len;
@@ -97,6 +104,21 @@ static void parse_whitespace_option(const char *option)
 	die("unrecognized whitespace option '%s'", option);
 }
 
+static void parse_ignorewhitespace_option(const char *option)
+{
+	if (!option || !strcmp(option, "no") ||
+	    !strcmp(option, "false") || !strcmp(option, "never") ||
+	    !strcmp(option, "none")) {
+		ws_ignore_action = ignore_ws_none;
+		return;
+	}
+	if (!strcmp(option, "change")) {
+		ws_ignore_action = ignore_ws_change;
+		return;
+	}
+	die("unrecognized whitespace ignore option '%s'", option);
+}
+
 static void set_default_whitespace_mode(const char *whitespace_option)
 {
 	if (!whitespace_option && !apply_default_whitespace)
@@ -214,6 +236,62 @@ static uint32_t hash_line(const char *cp, size_t len)
 	return h;
 }
 
+/*
+ * Compare lines s1 of length n1 and s2 of length n2, ignoring
+ * whitespace difference. Returns 1 if they match, 0 otherwise
+ */
+static int fuzzy_matchlines(const char *s1, size_t n1,
+			    const char *s2, size_t n2)
+{
+	const char *last1 = s1 + n1 - 1;
+	const char *last2 = s2 + n2 - 1;
+	int result = 0;
+
+	if (n1 < 0 || n2 < 0)
+		return 0;
+
+	/* ignore line endings */
+	while ((*last1 == '\r') || (*last1 == '\n'))
+		last1--;
+	while ((*last2 == '\r') || (*last2 == '\n'))
+		last2--;
+
+	/* skip leading whitespace */
+	while (isspace(*s1) && (s1 <= last1))
+		s1++;
+	while (isspace(*s2) && (s2 <= last2))
+		s2++;
+	/* early return if both lines are empty */
+	if ((s1 > last1) && (s2 > last2))
+		return 1;
+	while (!result) {
+		result = *s1++ - *s2++;
+		/*
+		 * Skip whitespace inside. We check for whitespace on
+		 * both buffers because we don't want "a b" to match
+		 * "ab"
+		 */
+		if (isspace(*s1) && isspace(*s2)) {
+			while (isspace(*s1) && s1 <= last1)
+				s1++;
+			while (isspace(*s2) && s2 <= last2)
+				s2++;
+		}
+		/*
+		 * If we reached the end on one side only,
+		 * lines don't match
+		 */
+		if (
+		    ((s2 > last2) && (s1 <= last1)) ||
+		    ((s1 > last1) && (s2 <= last2)))
+			return 0;
+		if ((s1 > last1) && (s2 > last2))
+			break;
+	}
+
+	return !result;
+}
+
 static void add_line_info(struct image *img, const char *bol, size_t len, unsigned flag)
 {
 	ALLOC_GROW(img->line_allocated, img->nr + 1, img->alloc);
@@ -1592,10 +1670,17 @@ static int read_old_data(struct stat *st, const char *path, struct strbuf *buf)
 	}
 }
 
+/*
+ * Update the preimage, and the common lines in postimage,
+ * from buffer buf of length len. If postlen is 0 the postimage
+ * is updated in place, otherwise it's updated on a new buffer
+ * of length postlen
+ */
+
 static void update_pre_post_images(struct image *preimage,
 				   struct image *postimage,
 				   char *buf,
-				   size_t len)
+				   size_t len, size_t postlen)
 {
 	int i, ctx;
 	char *new, *old, *fixed;
@@ -1614,11 +1699,19 @@ static void update_pre_post_images(struct image *preimage,
 	*preimage = fixed_preimage;
 
 	/*
-	 * Adjust the common context lines in postimage, in place.
-	 * This is possible because whitespace fixing does not make
-	 * the string grow.
+	 * Adjust the common context lines in postimage. This can be
+	 * done in-place when we are just doing whitespace fixing,
+	 * which does not make the string grow, but needs a new buffer
+	 * when ignoring whitespace causes the update, since in this case
+	 * we could have e.g. tabs converted to multiple spaces.
+	 * We trust the caller to tell us if the update can be done
+	 * in place (postlen==0) or not.
 	 */
-	new = old = postimage->buf;
+	old = postimage->buf;
+	if (postlen)
+		new = postimage->buf = xmalloc(postlen);
+	else
+		new = old;
 	fixed = preimage->buf;
 	for (i = ctx = 0; i < postimage->nr; i++) {
 		size_t len = postimage->line[i].len;
@@ -1693,12 +1786,58 @@ static int match_fragment(struct image *img,
 	    !memcmp(img->buf + try, preimage->buf, preimage->len))
 		return 1;
 
+	/*
+	 * No exact match. If we are ignoring whitespace, run a line-by-line
+	 * fuzzy matching. We collect all the line length information because
+	 * we need it to adjust whitespace if we match.
+	 */
+	if (ws_ignore_action == ignore_ws_change) {
+		size_t imgoff = 0;
+		size_t preoff = 0;
+		size_t postlen = postimage->len;
+		size_t imglen[preimage->nr];
+		for (i = 0; i < preimage->nr; i++) {
+			size_t prelen = preimage->line[i].len;
+
+			imglen[i] = img->line[try_lno+i].len;
+			if (!fuzzy_matchlines(
+				img->buf + try + imgoff, imglen[i],
+				preimage->buf + preoff, prelen))
+				return 0;
+			if (preimage->line[i].flag & LINE_COMMON)
+				postlen += imglen[i] - prelen;
+			imgoff += imglen[i];
+			preoff += prelen;
+		}
+
+		/*
+		 * Ok, the preimage matches with whitespace fuzz. Update it and
+		 * the common postimage lines to use the same whitespace as the
+		 * target. imgoff now holds the true length of the target that
+		 * matches the preimage, and we need to update the line lengths
+		 * of the preimage to match the target ones.
+		 */
+		fixed_buf = xmalloc(imgoff);
+		memcpy(fixed_buf, img->buf + try, imgoff);
+		for (i = 0; i < preimage->nr; i++)
+			preimage->line[i].len = imglen[i];
+
+		/*
+		 * Update the preimage buffer and the postimage context lines.
+		 */
+		update_pre_post_images(preimage, postimage,
+				fixed_buf, imgoff, postlen);
+		return 1;
+	}
+
 	if (ws_error_action != correct_ws_error)
 		return 0;
 
 	/*
 	 * The hunk does not apply byte-by-byte, but the hash says
-	 * it might with whitespace fuzz.
+	 * it might with whitespace fuzz. We haven't been asked to
+	 * ignore whitespace, we were asked to correct whitespace
+	 * errors, so let's try matching after whitespace correction.
 	 */
 	fixed_buf = xmalloc(preimage->len + 1);
 	buf = fixed_buf;
@@ -1750,7 +1889,7 @@ static int match_fragment(struct image *img,
 	 * hunk match.  Update the context lines in the postimage.
 	 */
 	update_pre_post_images(preimage, postimage,
-			       fixed_buf, buf - fixed_buf);
+			       fixed_buf, buf - fixed_buf, 0);
 	return 1;
 
  unmatch_exit:
@@ -3192,6 +3331,8 @@ static int git_apply_config(const char *var, const char *value, void *cb)
 {
 	if (!strcmp(var, "apply.whitespace"))
 		return git_config_string(&apply_default_whitespace, var, value);
+	else if (!strcmp(var, "apply.ignorewhitespace"))
+		return git_config_string(&apply_default_ignorewhitespace, var, value);
 	return git_default_config(var, value, cb);
 }
 
@@ -3228,6 +3369,16 @@ static int option_parse_z(const struct option *opt,
 	return 0;
 }
 
+static int option_parse_space_change(const struct option *opt,
+			  const char *arg, int unset)
+{
+	if (unset)
+		ws_ignore_action = ignore_ws_none;
+	else
+		ws_ignore_action = ignore_ws_change;
+	return 0;
+}
+
 static int option_parse_whitespace(const struct option *opt,
 				   const char *arg, int unset)
 {
@@ -3304,6 +3455,12 @@ int cmd_apply(int argc, const char **argv, const char *unused_prefix)
 		{ OPTION_CALLBACK, 0, "whitespace", &whitespace_option, "action",
 			"detect new or modified lines that have whitespace errors",
 			0, option_parse_whitespace },
+		{ OPTION_CALLBACK, 0, "ignore-space-change", NULL, NULL,
+			"ignore changes in whitespace when finding context",
+			PARSE_OPT_NOARG, option_parse_space_change },
+		{ OPTION_CALLBACK, 0, "ignore-whitespace", NULL, NULL,
+			"ignore changes in whitespace when finding context",
+			PARSE_OPT_NOARG, option_parse_space_change },
 		OPT_BOOLEAN('R', "reverse", &apply_in_reverse,
 			"apply the patch in reverse"),
 		OPT_BOOLEAN(0, "unidiff-zero", &unidiff_zero,
@@ -3328,6 +3485,8 @@ int cmd_apply(int argc, const char **argv, const char *unused_prefix)
 	git_config(git_apply_config, NULL);
 	if (apply_default_whitespace)
 		parse_whitespace_option(apply_default_whitespace);
+	if (apply_default_ignorewhitespace)
+		parse_ignorewhitespace_option(apply_default_ignorewhitespace);
 
 	argc = parse_options(argc, argv, prefix, builtin_apply_options,
 			apply_usage, 0);
diff --git a/cache.h b/cache.h
index e6c7f3307d..695212fca9 100644
--- a/cache.h
+++ b/cache.h
@@ -509,6 +509,7 @@ extern int log_all_ref_updates;
 extern int warn_ambiguous_refs;
 extern int shared_repository;
 extern const char *apply_default_whitespace;
+extern const char *apply_default_ignorewhitespace;
 extern int zlib_compression_level;
 extern int core_compression_level;
 extern int core_compression_seen;
diff --git a/contrib/completion/git-completion.bash b/contrib/completion/git-completion.bash
index 745b5fb78b..dd7ec5dd66 100755
--- a/contrib/completion/git-completion.bash
+++ b/contrib/completion/git-completion.bash
@@ -674,6 +674,7 @@ _git_am ()
 	--*)
 		__gitcomp "
 			--3way --committer-date-is-author-date --ignore-date
+			--ignore-whitespace --ignore-space-change
 			--interactive --keep --no-utf8 --signoff --utf8
 			--whitespace=
 			"
@@ -695,6 +696,7 @@ _git_apply ()
 			--stat --numstat --summary --check --index
 			--cached --index-info --reverse --reject --unidiff-zero
 			--apply --no-add --exclude=
+			--ignore-whitespace --ignore-space-change
 			--whitespace= --inaccurate-eof --verbose
 			"
 		return
@@ -1536,6 +1538,7 @@ _git_config ()
 	__gitcomp "
 		add.ignore-errors
 		alias.
+		apply.ignorewhitespace
 		apply.whitespace
 		branch.autosetupmerge
 		branch.autosetuprebase
diff --git a/environment.c b/environment.c
index 8f5eaa7dd8..3cf88f58c4 100644
--- a/environment.c
+++ b/environment.c
@@ -26,6 +26,7 @@ const char *git_commit_encoding;
 const char *git_log_output_encoding;
 int shared_repository = PERM_UMASK;
 const char *apply_default_whitespace;
+const char *apply_default_ignorewhitespace;
 int zlib_compression_level = Z_BEST_SPEED;
 int core_compression_level;
 int core_compression_seen;
diff --git a/git-am.sh b/git-am.sh
index d64d997535..ab39b3c2fa 100755
--- a/git-am.sh
+++ b/git-am.sh
@@ -16,6 +16,8 @@ s,signoff       add a Signed-off-by line to the commit message
 u,utf8          recode into utf8 (default)
 k,keep          pass -k flag to git-mailinfo
 whitespace=     pass it through git-apply
+ignore-space-change pass it through git-apply
+ignore-whitespace pass it through git-apply
 directory=      pass it through git-apply
 C=              pass it through git-apply
 p=              pass it through git-apply
@@ -303,7 +305,7 @@ do
 		git_apply_opt="$git_apply_opt $(sq "$1$2")"; shift ;;
 	--patch-format)
 		shift ; patch_format="$1" ;;
-	--reject)
+	--reject|--ignore-whitespace|--ignore-space-change)
 		git_apply_opt="$git_apply_opt $1" ;;
 	--committer-date-is-author-date)
 		committer_date_is_author_date=t ;;
diff --git a/git-rebase.sh b/git-rebase.sh
index 18bc6946cf..d741752c7c 100755
--- a/git-rebase.sh
+++ b/git-rebase.sh
@@ -333,6 +333,9 @@ do
 			;;
 		esac
 		;;
+	--ignore-whitespace)
+		git_am_opt="$git_am_opt $1"
+		;;
 	--committer-date-is-author-date|--ignore-date)
 		git_am_opt="$git_am_opt $1"
 		force_rebase=t
diff --git a/t/t4107-apply-ignore-whitespace.sh b/t/t4107-apply-ignore-whitespace.sh
new file mode 100755
index 0000000000..484654d6e4
--- /dev/null
+++ b/t/t4107-apply-ignore-whitespace.sh
@@ -0,0 +1,185 @@
+#!/bin/sh
+#
+# Copyright (c) 2009 Giuseppe Bilotta
+#
+
+test_description='git-apply --ignore-whitespace.
+
+'
+. ./test-lib.sh
+
+# This primes main.c file that indents without using HT at all.
+# Various patches with HT and other spaces are attempted in the test.
+
+cat > patch1.patch <<\EOF
+diff --git a/main.c b/main.c
+new file mode 100644
+--- /dev/null
++++ b/main.c
+@@ -0,0 +1,22 @@
++#include <stdio.h>
++
++void print_int(int num);
++int func(int num);
++
++int main() {
++       int i;
++
++       for (i = 0; i < 10; i++) {
++               print_int(func(i)); /* stuff */
++       }
++
++       return 0;
++}
++
++int func(int num) {
++       return num * num;
++}
++
++void print_int(int num) {
++       printf("%d", num);
++}
+EOF
+
+# Since whitespace is very significant and we want to prevent whitespace
+# mangling when creating this test from a patch, we protect 'fixable'
+# whitespace by replacing spaces with Z and replacing them at patch
+# creation time, hence the sed trick.
+
+# This patch will fail unless whitespace differences are being ignored
+
+sed -e 's/Z/ /g' > patch2.patch <<\EOF
+diff --git a/main.c b/main.c
+--- a/main.c
++++ b/main.c
+@@ -10,6 +10,8 @@
+Z		print_int(func(i)); /* stuff */
+Z	}
+Z
++	printf("\n");
++
+Z	return 0;
+Z}
+Z
+EOF
+
+# This patch will fail even if whitespace differences are being ignored,
+# because of the missing string at EOL. TODO: this testcase should be
+# improved by creating a line that has the same hash with and without
+# the final string.
+
+sed -e 's/Z/ /g' > patch3.patch <<\EOF
+diff --git a/main.c b/main.c
+--- a/main.c
++++ b/main.c
+@@ -10,3 +10,4 @@
+Z	for (i = 0; i < 10; i++) {
+Z		print_int(func(i));Z
++		/* stuff */
+Z	}
+EOF
+
+# This patch will fail even if whitespace differences are being ignored,
+# because of the missing EOL at EOF.
+
+sed -e 's/Z/ /g' > patch4.patch <<\EOF
+diff --git a/main.c b/main.c
+--- a/main.c
++++ b/main.c
+@@ -21,1 +21,1 @@
+-	};Z
+\ No newline at end of file
++	};
+EOF
+
+# This patch will fail unless whitespace differences are being ignored.
+
+sed -e 's/Z/ /g' > patch5.patch <<\EOF
+diff --git a/main.c b/main.c
+--- a/main.c
++++ b/main.c
+@@ -2,2 +2,3 @@
+Z	void print_int(int num);
++	/* a comment */
+Z	int func(int num);
+EOF
+
+# And this is how the final output should be.  Patches introduce
+# HTs but the original SP indents are mostly kept.
+
+sed -e 's/T/	/g' > main.c.final <<\EOF
+#include <stdio.h>
+
+void print_int(int num);
+T/* a comment */
+int func(int num);
+
+int main() {
+       int i;
+
+       for (i = 0; i < 10; i++) {
+               print_int(func(i)); /* stuff */
+       }
+
+Tprintf("\n");
+
+       return 0;
+}
+
+int func(int num) {
+       return num * num;
+}
+
+void print_int(int num) {
+       printf("%d", num);
+}
+EOF
+
+test_expect_success 'file creation' '
+	git-apply patch1.patch
+'
+
+test_expect_success 'patch2 fails (retab)' '
+	test_must_fail git-apply patch2.patch
+'
+
+test_expect_success 'patch2 applies with --ignore-whitespace' '
+	git-apply --ignore-whitespace patch2.patch
+'
+
+test_expect_success 'patch2 reverse applies with --ignore-space-change' '
+	git-apply -R --ignore-space-change patch2.patch
+'
+
+git config apply.ignorewhitespace change
+
+test_expect_success 'patch2 applies (apply.ignorewhitespace = change)' '
+	git-apply patch2.patch
+'
+
+test_expect_success 'patch3 fails (missing string at EOL)' '
+	test_must_fail git-apply patch3.patch
+'
+
+test_expect_success 'patch4 fails (missing EOL at EOF)' '
+	test_must_fail git-apply patch4.patch
+'
+
+test_expect_success 'patch5 applies (leading whitespace)' '
+	git-apply patch5.patch
+'
+
+test_expect_success 'patches do not mangle whitespace' '
+	test_cmp main.c main.c.final
+'
+
+test_expect_success 're-create file (with --ignore-whitespace)' '
+	rm -f main.c &&
+	git-apply patch1.patch
+'
+
+test_expect_success 'patch5 fails (--no-ignore-whitespace)' '
+	test_must_fail git-apply --no-ignore-whitespace patch5.patch
+'
+
+test_done