diff --git a/t/t0021-conversion.sh b/t/t0021-conversion.sh
index e50f0f742..b92e6cb04 100755
--- a/t/t0021-conversion.sh
+++ b/t/t0021-conversion.sh
@@ -190,4 +190,18 @@ test_expect_success 'required filter clean failure' '
 	test_must_fail git add test.fc
 '
 
+test -n "$GIT_TEST_LONG" && test_set_prereq EXPENSIVE
+
+test_expect_success EXPENSIVE 'filter large file' '
+	git config filter.largefile.smudge cat &&
+	git config filter.largefile.clean cat &&
+	for i in $(test_seq 1 2048); do printf "%1048576d" 1; done >2GB &&
+	echo "2GB filter=largefile" >.gitattributes &&
+	git add 2GB 2>err &&
+	! test -s err &&
+	rm -f 2GB &&
+	git checkout -- 2GB 2>err &&
+	! test -s err
+'
+
 test_done
diff --git a/wrapper.c b/wrapper.c
index 6a015de5f..f92b14759 100644
--- a/wrapper.c
+++ b/wrapper.c
@@ -130,6 +130,14 @@ void *xcalloc(size_t nmemb, size_t size)
 	return ret;
 }
 
+/*
+ * Limit size of IO chunks, because huge chunks only cause pain.  OS X
+ * 64-bit is buggy, returning EINVAL if len >= INT_MAX; and even in
+ * the absense of bugs, large chunks can result in bad latencies when
+ * you decide to kill the process.
+ */
+#define MAX_IO_SIZE (8*1024*1024)
+
 /*
  * xread() is the same a read(), but it automatically restarts read()
  * operations with a recoverable error (EAGAIN and EINTR). xread()
@@ -138,6 +146,8 @@ void *xcalloc(size_t nmemb, size_t size)
 ssize_t xread(int fd, void *buf, size_t len)
 {
 	ssize_t nr;
+	if (len > MAX_IO_SIZE)
+	    len = MAX_IO_SIZE;
 	while (1) {
 		nr = read(fd, buf, len);
 		if ((nr < 0) && (errno == EAGAIN || errno == EINTR))
@@ -154,6 +164,8 @@ ssize_t xread(int fd, void *buf, size_t len)
 ssize_t xwrite(int fd, const void *buf, size_t len)
 {
 	ssize_t nr;
+	if (len > MAX_IO_SIZE)
+	    len = MAX_IO_SIZE;
 	while (1) {
 		nr = write(fd, buf, len);
 		if ((nr < 0) && (errno == EAGAIN || errno == EINTR))