diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index 2f7f54a..506581a 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -4626,6 +4626,26 @@
   return Param;
 }
 
+void Sema::DiagnoseUnusedParameters(ParmVarDecl * const *Param,
+                                    ParmVarDecl * const *ParamEnd) {
+  if (Diags.getDiagnosticLevel(diag::warn_unused_parameter) ==
+        Diagnostic::Ignored)
+    return;
+
+  // Don't diagnose unused-parameter errors in template instantiations; we
+  // will already have done so in the template itself.
+  if (!ActiveTemplateInstantiations.empty())
+    return;
+
+  for (; Param != ParamEnd; ++Param) {
+    if (!(*Param)->isUsed() && (*Param)->getDeclName() &&
+        !(*Param)->hasAttr<UnusedAttr>()) {
+      Diag((*Param)->getLocation(), diag::warn_unused_parameter)
+        << (*Param)->getDeclName();
+    }
+  }
+}
+
 ParmVarDecl *Sema::CheckParameter(DeclContext *DC, 
                                   TypeSourceInfo *TSInfo, QualType T,
                                   IdentifierInfo *Name,