diff --git a/Makefile b/Makefile
index e3405dc3a7..fd5c80f753 100644
--- a/Makefile
+++ b/Makefile
@@ -35,7 +35,7 @@ PROG=   git-update-cache git-diff-files git-init-db git-write-tree \
 	git-http-pull git-ssh-push git-ssh-pull git-rev-list git-mktag \
 	git-diff-helper git-tar-tree git-local-pull git-write-blob \
 	git-get-tar-commit-id git-mkdelta git-apply git-stripspace \
-	git-cvs2git git-diff-stages git-rev-parse
+	git-cvs2git git-diff-stages git-rev-parse git-patch-id
 
 all: $(PROG)
 
@@ -121,6 +121,7 @@ git-stripspace: stripspace.c
 git-cvs2git: cvs2git.c
 git-diff-stages: diff-stages.c
 git-rev-parse: rev-parse.c
+git-patch-id: patch-id.c
 
 git-http-pull: LIBS += -lcurl
 git-rev-list: LIBS += -lssl
diff --git a/patch-id.c b/patch-id.c
new file mode 100644
index 0000000000..0bd640cc48
--- /dev/null
+++ b/patch-id.c
@@ -0,0 +1,79 @@
+#include <ctype.h>
+#include "cache.h"
+
+static void flush_current_id(int patchlen, unsigned char *id, SHA_CTX *c)
+{
+	unsigned char result[20];
+	char name[50];
+
+	if (!patchlen)
+		return;
+
+	SHA1_Final(result, c);
+	memcpy(name, sha1_to_hex(id), 41);
+	printf("%s %s\n", sha1_to_hex(result), name);
+	SHA1_Init(c);
+}
+
+static int remove_space(char *line)
+{
+	char *src = line;
+	char *dst = line;
+	unsigned char c;
+
+	while ((c = *src++) != '\0') {
+		if (!isspace(c))
+			*dst++ = c;
+	}
+	return dst - line;
+}
+
+static void generate_id_list(void)
+{
+	static unsigned char sha1[20];
+	static char line[1000];
+	SHA_CTX ctx;
+	int patchlen = 0;
+
+	SHA1_Init(&ctx);
+	while (fgets(line, sizeof(line), stdin) != NULL) {
+		unsigned char n[20];
+		char *p = line;
+		int len;
+
+		if (!memcmp(line, "diff-tree ", 10))
+			p += 10;
+
+		if (!get_sha1_hex(p, n)) {
+			flush_current_id(patchlen, sha1, &ctx);
+			memcpy(sha1, n, 20);
+			patchlen = 0;
+			continue;
+		}
+
+		/* Ignore commit comments */
+		if (!patchlen && memcmp(line, "diff ", 5))
+			continue;
+
+		/* Ignore line numbers when computing the SHA1 of the patch */
+		if (!memcmp(line, "@@ -", 4))
+			continue;
+
+		/* Compute the sha without whitespace */
+		len = remove_space(line);
+		patchlen += len;
+		SHA1_Update(&ctx, line, len);
+	}
+	flush_current_id(patchlen, sha1, &ctx);
+}
+
+static const char patch_id_usage[] = "usage: git-patch-id < patch";
+
+int main(int argc, char **argv)
+{
+	if (argc != 1)
+		usage(patch_id_usage);
+
+	generate_id_list();
+	return 0;
+}