diff --git a/convert.c b/convert.c
index 33373b3ac0..4534e2c2b0 100644
--- a/convert.c
+++ b/convert.c
@@ -196,9 +196,17 @@ static int crlf_to_git(const char *path, const char *src, size_t len,
 	char *dst;
 
 	if (crlf_action == CRLF_BINARY ||
-	    (crlf_action == CRLF_GUESS && auto_crlf == AUTO_CRLF_FALSE) || !len)
+	    (crlf_action == CRLF_GUESS && auto_crlf == AUTO_CRLF_FALSE) ||
+	    (src && !len))
 		return 0;
 
+	/*
+	 * If we are doing a dry-run and have no source buffer, there is
+	 * nothing to analyze; we must assume we would convert.
+	 */
+	if (!buf && !src)
+		return 1;
+
 	gather_stats(src, len, &stats);
 
 	if (crlf_action == CRLF_AUTO || crlf_action == CRLF_GUESS) {
@@ -232,6 +240,13 @@ static int crlf_to_git(const char *path, const char *src, size_t len,
 	if (!stats.cr)
 		return 0;
 
+	/*
+	 * At this point all of our source analysis is done, and we are sure we
+	 * would convert. If we are in dry-run mode, we can give an answer.
+	 */
+	if (!buf)
+		return 1;
+
 	/* only grow if not in place */
 	if (strbuf_avail(buf) + buf->len < len)
 		strbuf_grow(buf, len - buf->len);
@@ -396,6 +411,9 @@ static int apply_filter(const char *path, const char *src, size_t len,
 	if (!cmd)
 		return 0;
 
+	if (!dst)
+		return 1;
+
 	memset(&async, 0, sizeof(async));
 	async.proc = filter_buffer;
 	async.data = &params;
@@ -527,9 +545,12 @@ static int ident_to_git(const char *path, const char *src, size_t len,
 {
 	char *dst, *dollar;
 
-	if (!ident || !count_ident(src, len))
+	if (!ident || (src && !count_ident(src, len)))
 		return 0;
 
+	if (!buf)
+		return 1;
+
 	/* only grow if not in place */
 	if (strbuf_avail(buf) + buf->len < len)
 		strbuf_grow(buf, len - buf->len);
@@ -759,13 +780,13 @@ int convert_to_git(const char *path, const char *src, size_t len,
 		filter = ca.drv->clean;
 
 	ret |= apply_filter(path, src, len, dst, filter);
-	if (ret) {
+	if (ret && dst) {
 		src = dst->buf;
 		len = dst->len;
 	}
 	ca.crlf_action = input_crlf_action(ca.crlf_action, ca.eol_attr);
 	ret |= crlf_to_git(path, src, len, dst, ca.crlf_action, checksafe);
-	if (ret) {
+	if (ret && dst) {
 		src = dst->buf;
 		len = dst->len;
 	}
diff --git a/convert.h b/convert.h
index d799a165b4..ec5fd69430 100644
--- a/convert.h
+++ b/convert.h
@@ -40,6 +40,11 @@ extern int convert_to_working_tree(const char *path, const char *src,
 				   size_t len, struct strbuf *dst);
 extern int renormalize_buffer(const char *path, const char *src, size_t len,
 			      struct strbuf *dst);
+static inline int would_convert_to_git(const char *path, const char *src,
+				       size_t len, enum safe_crlf checksafe)
+{
+	return convert_to_git(path, src, len, NULL, checksafe);
+}
 
 /*****************************************************************
  *
diff --git a/sha1_file.c b/sha1_file.c
index f9f8d5e91c..4f06a0e450 100644
--- a/sha1_file.c
+++ b/sha1_file.c
@@ -2700,10 +2700,13 @@ static int index_core(unsigned char *sha1, int fd, size_t size,
  * This also bypasses the usual "convert-to-git" dance, and that is on
  * purpose. We could write a streaming version of the converting
  * functions and insert that before feeding the data to fast-import
- * (or equivalent in-core API described above), but the primary
- * motivation for trying to stream from the working tree file and to
- * avoid mmaping it in core is to deal with large binary blobs, and
- * by definition they do _not_ want to get any conversion.
+ * (or equivalent in-core API described above). However, that is
+ * somewhat complicated, as we do not know the size of the filter
+ * result, which we need to know beforehand when writing a git object.
+ * Since the primary motivation for trying to stream from the working
+ * tree file and to avoid mmaping it in core is to deal with large
+ * binary blobs, they generally do not want to get any conversion, and
+ * callers should avoid this code path when filters are requested.
  */
 static int index_stream(unsigned char *sha1, int fd, size_t size,
 			enum object_type type, const char *path,
@@ -2720,7 +2723,8 @@ int index_fd(unsigned char *sha1, int fd, struct stat *st,
 
 	if (!S_ISREG(st->st_mode))
 		ret = index_pipe(sha1, fd, type, path, flags);
-	else if (size <= big_file_threshold || type != OBJ_BLOB)
+	else if (size <= big_file_threshold || type != OBJ_BLOB ||
+		 (path && would_convert_to_git(path, NULL, 0, 0)))
 		ret = index_core(sha1, fd, size, type, path, flags);
 	else
 		ret = index_stream(sha1, fd, size, type, path, flags);
diff --git a/t/t1051-large-conversion.sh b/t/t1051-large-conversion.sh
new file mode 100755
index 0000000000..8b7640b3ba
--- /dev/null
+++ b/t/t1051-large-conversion.sh
@@ -0,0 +1,86 @@
+#!/bin/sh
+
+test_description='test conversion filters on large files'
+. ./test-lib.sh
+
+set_attr() {
+	test_when_finished 'rm -f .gitattributes' &&
+	echo "* $*" >.gitattributes
+}
+
+check_input() {
+	git read-tree --empty &&
+	git add small large &&
+	git cat-file blob :small >small.index &&
+	git cat-file blob :large | head -n 1 >large.index &&
+	test_cmp small.index large.index
+}
+
+check_output() {
+	rm -f small large &&
+	git checkout small large &&
+	head -n 1 large >large.head &&
+	test_cmp small large.head
+}
+
+test_expect_success 'setup input tests' '
+	printf "\$Id: foo\$\\r\\n" >small &&
+	cat small small >large &&
+	git config core.bigfilethreshold 20 &&
+	git config filter.test.clean "sed s/.*/CLEAN/"
+'
+
+test_expect_success 'autocrlf=true converts on input' '
+	test_config core.autocrlf true &&
+	check_input
+'
+
+test_expect_success 'eol=crlf converts on input' '
+	set_attr eol=crlf &&
+	check_input
+'
+
+test_expect_success 'ident converts on input' '
+	set_attr ident &&
+	check_input
+'
+
+test_expect_success 'user-defined filters convert on input' '
+	set_attr filter=test &&
+	check_input
+'
+
+test_expect_success 'setup output tests' '
+	echo "\$Id\$" >small &&
+	cat small small >large &&
+	git add small large &&
+	git config core.bigfilethreshold 7 &&
+	git config filter.test.smudge "sed s/.*/SMUDGE/"
+'
+
+test_expect_success 'autocrlf=true converts on output' '
+	test_config core.autocrlf true &&
+	check_output
+'
+
+test_expect_success 'eol=crlf converts on output' '
+	set_attr eol=crlf &&
+	check_output
+'
+
+test_expect_success 'user-defined filters convert on output' '
+	set_attr filter=test &&
+	check_output
+'
+
+test_expect_success 'ident converts on output' '
+	set_attr ident &&
+	rm -f small large &&
+	git checkout small large &&
+	sed -n "s/Id: .*/Id: SHA/p" <small >small.clean &&
+	head -n 1 large >large.head &&
+	sed -n "s/Id: .*/Id: SHA/p" <large.head >large.clean &&
+	test_cmp small.clean large.clean
+'
+
+test_done