diff --git a/test/CFrontend/2008-01-07-UnusualIntSize.c b/test/CFrontend/2008-01-07-UnusualIntSize.c
new file mode 100644
index 00000000000..924ae2ba37d
--- /dev/null
+++ b/test/CFrontend/2008-01-07-UnusualIntSize.c
@@ -0,0 +1,11 @@
+// RUN: %llvmgcc %s -S -o - -O | grep {and.*8589934591}
+// PR1721
+
+struct s {
+  unsigned long long u33: 33;
+} a, b;
+
+// This should turn into a real 33-bit add, not a 64-bit add.
+_Bool test(void) {
+  return a.u33 + b.u33 != 0;
+}