diff --git a/llvm/include/llvm/ADT/StringExtras.h b/llvm/include/llvm/ADT/StringExtras.h
index 30397b23ab03b..091a40dc8afd5 100644
--- a/llvm/include/llvm/ADT/StringExtras.h
+++ b/llvm/include/llvm/ADT/StringExtras.h
@@ -418,7 +418,7 @@ inline std::string join_impl(IteratorT Begin, IteratorT End,
 
   size_t Len = (std::distance(Begin, End) - 1) * Separator.size();
   for (IteratorT I = Begin; I != End; ++I)
-    Len += (*I).size();
+    Len += StringRef(*I).size();
   S.reserve(Len);
   size_t PrevCapacity = S.capacity();
   (void)PrevCapacity;
diff --git a/llvm/unittests/ADT/StringExtrasTest.cpp b/llvm/unittests/ADT/StringExtrasTest.cpp
index 971560b8eb8c4..3f69c91b270a3 100644
--- a/llvm/unittests/ADT/StringExtrasTest.cpp
+++ b/llvm/unittests/ADT/StringExtrasTest.cpp
@@ -59,8 +59,8 @@ TEST(StringExtrasTest, isUpper) {
   EXPECT_FALSE(isUpper('\?'));
 }
 
-TEST(StringExtrasTest, Join) {
-  std::vector<std::string> Items;
+template <class ContainerT> void testJoin() {
+  ContainerT Items;
   EXPECT_EQ("", join(Items.begin(), Items.end(), " <sep> "));
 
   Items = {"foo"};
@@ -74,6 +74,17 @@ TEST(StringExtrasTest, Join) {
             join(Items.begin(), Items.end(), " <sep> "));
 }
 
+TEST(StringExtrasTest, Join) {
+  {
+    SCOPED_TRACE("std::vector<std::string>");
+    testJoin<std::vector<std::string>>();
+  }
+  {
+    SCOPED_TRACE("std::vector<const char*>");
+    testJoin<std::vector<const char *>>();
+  }
+}
+
 TEST(StringExtrasTest, JoinItems) {
   const char *Foo = "foo";
   std::string Bar = "bar";