diff --git a/lib/Support/StringRef.cpp b/lib/Support/StringRef.cpp
index 4bafc4ec718..d7fa99dbde2 100644
--- a/lib/Support/StringRef.cpp
+++ b/lib/Support/StringRef.cpp
@@ -374,9 +374,14 @@ size_t StringRef::count(StringRef Str) const {
   size_t N = Str.size();
   if (N > Length)
     return 0;
-  for (size_t i = 0, e = Length - N + 1; i != e; ++i)
-    if (substr(i, N).equals(Str))
+  for (size_t i = 0, e = Length - N + 1; i < e;) {
+    if (substr(i, N).equals(Str)) {
       ++Count;
+      i += N;
+    }
+    else
+      ++i;
+  }
   return Count;
 }
 
diff --git a/unittests/ADT/StringRefTest.cpp b/unittests/ADT/StringRefTest.cpp
index 2e5159dde1c..cbb2a30ff17 100644
--- a/unittests/ADT/StringRefTest.cpp
+++ b/unittests/ADT/StringRefTest.cpp
@@ -509,6 +509,13 @@ TEST(StringRefTest, Count) {
   EXPECT_EQ(1U, Str.count("hello"));
   EXPECT_EQ(1U, Str.count("ello"));
   EXPECT_EQ(0U, Str.count("zz"));
+
+  StringRef OverlappingAbba("abbabba");
+  EXPECT_EQ(1U, OverlappingAbba.count("abba"));
+  StringRef NonOverlappingAbba("abbaabba");
+  EXPECT_EQ(2U, NonOverlappingAbba.count("abba"));
+  StringRef ComplexAbba("abbabbaxyzabbaxyz");
+  EXPECT_EQ(2U, ComplexAbba.count("abba"));
 }
 
 TEST(StringRefTest, EditDistance) {