diff --git a/cmake/modules/HandleLLVMOptions.cmake b/cmake/modules/HandleLLVMOptions.cmake
index f4ac6d7a73f..d583d0ee95c 100644
--- a/cmake/modules/HandleLLVMOptions.cmake
+++ b/cmake/modules/HandleLLVMOptions.cmake
@@ -391,16 +391,23 @@ elseif( LLVM_COMPILER_IS_GCC_COMPATIBLE )
     # Check if -Wnon-virtual-dtor warns even though the class is marked final.
     # If it does, don't add it. So it won't be added on clang 3.4 and older.
     # This also catches cases when -Wnon-virtual-dtor isn't supported by
-    # the compiler at all.
-    set(OLD_CMAKE_REQUIRED_FLAGS ${CMAKE_REQUIRED_FLAGS})
-    set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -std=c++11 -Werror=non-virtual-dtor")
-    CHECK_CXX_SOURCE_COMPILES("class base {public: virtual void anchor();protected: ~base();};
-                               class derived final : public base { public: ~derived();};
-                               int main() { return 0; }"
-                              CXX_WONT_WARN_ON_FINAL_NONVIRTUALDTOR)
-    set(CMAKE_REQUIRED_FLAGS ${OLD_CMAKE_REQUIRED_FLAGS})
-    append_if(CXX_WONT_WARN_ON_FINAL_NONVIRTUALDTOR
-              "-Wnon-virtual-dtor" CMAKE_CXX_FLAGS)
+    # the compiler at all.  This flag is not activated for gcc since it will
+    # incorrectly identify a protected non-virtual base when there is a friend
+    # declaration.
+    if (NOT CMAKE_COMPILER_IS_GNUCXX)
+      set(OLD_CMAKE_REQUIRED_FLAGS ${CMAKE_REQUIRED_FLAGS})
+      set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -std=c++11 -Werror=non-virtual-dtor")
+      CHECK_CXX_SOURCE_COMPILES("class base {public: virtual void anchor();protected: ~base();};
+                                 class derived final : public base { public: ~derived();};
+                                 int main() { return 0; }"
+                                CXX_WONT_WARN_ON_FINAL_NONVIRTUALDTOR)
+      set(CMAKE_REQUIRED_FLAGS ${OLD_CMAKE_REQUIRED_FLAGS})
+      append_if(CXX_WONT_WARN_ON_FINAL_NONVIRTUALDTOR
+                "-Wnon-virtual-dtor" CMAKE_CXX_FLAGS)
+    endif()
+
+    # Enable -Wdelete-non-virtual-dtor if available.
+    add_flag_if_supported("-Wdelete-non-virtual-dtor" DELETE_NON_VIRTUAL_DTOR_FLAG)
 
     # Check if -Wcomment is OK with an // comment ending with '\' if the next
     # line is also a // comment.
diff --git a/include/llvm/Analysis/ScalarEvolution.h b/include/llvm/Analysis/ScalarEvolution.h
index 15565daf6d3..012fafb67a4 100644
--- a/include/llvm/Analysis/ScalarEvolution.h
+++ b/include/llvm/Analysis/ScalarEvolution.h
@@ -183,7 +183,7 @@ namespace llvm {
 
   protected:
     SCEVPredicateKind Kind;
-    virtual ~SCEVPredicate();
+    ~SCEVPredicate() = default;
     SCEVPredicate(const SCEVPredicate&) = default;
     SCEVPredicate &operator=(const SCEVPredicate&) = default;
 
diff --git a/lib/Analysis/ScalarEvolution.cpp b/lib/Analysis/ScalarEvolution.cpp
index 1c2fb3d1ed0..e5d8109fcbb 100644
--- a/lib/Analysis/ScalarEvolution.cpp
+++ b/lib/Analysis/ScalarEvolution.cpp
@@ -9628,8 +9628,6 @@ SCEVPredicate::SCEVPredicate(const FoldingSetNodeIDRef ID,
                              SCEVPredicateKind Kind)
     : FastID(ID), Kind(Kind) {}
 
-SCEVPredicate::~SCEVPredicate() {}
-
 SCEVEqualPredicate::SCEVEqualPredicate(const FoldingSetNodeIDRef ID,
                                        const SCEVUnknown *LHS,
                                        const SCEVConstant *RHS)