diff --git a/llvm/include/llvm/ADT/Twine.h b/llvm/include/llvm/ADT/Twine.h
--- a/llvm/include/llvm/ADT/Twine.h
+++ b/llvm/include/llvm/ADT/Twine.h
@@ -291,9 +291,9 @@
     /// Construct from an std::string_view by converting it to a pointer and
     /// length.  This handles string_views on a pure API basis, and avoids
     /// storing one (or a pointer to one) inside a Twine, which avoids problems
-    /// when mixing code compiled under various C++ standards.
-    /*implicit*/ Twine(const std::string_view &Str)
-        : LHSKind(PtrAndLengthKind) {
+    /// when mixing code compiled under various C++ standards. Pass string_view
+    /// by value is preferred.
+    /*implicit*/ Twine(std::string_view Str) : LHSKind(PtrAndLengthKind) {
       LHS.ptrAndLength.ptr = Str.data();
       LHS.ptrAndLength.length = Str.length();
       assert(isValid() && "Invalid twine!");