diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index 4208421..e9c3c39 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -9921,7 +9921,9 @@
       Diag(FD->getLocation(), diag::warn_pure_function_definition);
 
     if (!FD->isInvalidDecl()) {
-      DiagnoseUnusedParameters(FD->param_begin(), FD->param_end());
+      // Don't diagnose unused parameters of defaulted or deleted functions.
+      if (Body)
+        DiagnoseUnusedParameters(FD->param_begin(), FD->param_end());
       DiagnoseSizeOfParametersAndReturnValue(FD->param_begin(), FD->param_end(),
                                              FD->getReturnType(), FD);