Index: include/clang/Basic/DiagnosticDriverKinds.td
===================================================================
--- include/clang/Basic/DiagnosticDriverKinds.td
+++ include/clang/Basic/DiagnosticDriverKinds.td
@@ -163,9 +163,9 @@
 def warn_drv_enabling_rtti_with_exceptions : Warning<
   "implicitly enabling rtti for exception handling">,
   InGroup<DiagGroup<"rtti-for-exceptions">>;
-def warn_drv_disabling_vptr_no_rtti_default : Warning<
-  "implicitly disabling vptr sanitizer because rtti wasn't enabled">,
-  InGroup<DiagGroup<"auto-disable-vptr-sanitizer">>;
+def warn_drv_enabling_rtti_with_vptr: Warning<
+  "implicitly enabling rtti for the vptr sanitizer">,
+  InGroup<DiagGroup<"rtti-for-vptr-sanitizer">>;
 
 def note_drv_command_failed_diag_msg : Note<
   "diagnostic msg: %0">;
Index: lib/Driver/Tools.cpp
===================================================================
--- lib/Driver/Tools.cpp
+++ lib/Driver/Tools.cpp
@@ -4040,16 +4040,14 @@
     // -fno-rtti cannot usefully be combined with -fsanitize=vptr.
     if (Sanitize.sanitizesVptr()) {
       // If rtti was explicitly disabled and the vptr sanitizer is on, error
-      // out. Otherwise, warn that vptr will be disabled unless -frtti is
-      // passed.
+      // out. Otherwise, warn that rtti will be enabled because
+      // -fsanitize=vptr was passed.
       if (NoRTTIArg) {
         D.Diag(diag::err_drv_argument_not_allowed_with)
             << "-fsanitize=vptr" << NoRTTIArg->getAsString(Args);
       } else {
-        D.Diag(diag::warn_drv_disabling_vptr_no_rtti_default);
-        // All sanitizer switches have been pushed. This -fno-sanitize
-        // will override any -fsanitize={vptr,undefined} passed before it.
-        CmdArgs.push_back("-fno-sanitize=vptr");
+        RTTIEnabled = true;
+        D.Diag(diag::warn_drv_enabling_rtti_with_vptr);
       }
     }
 
Index: test/Driver/rtti-options.cpp
===================================================================
--- test/Driver/rtti-options.cpp
+++ test/Driver/rtti-options.cpp
@@ -4,43 +4,39 @@
 // the vptr sanitizer with -fno-rtti
 
 // -fsanitize=vptr
-// RUN: %clang -### -c -target x86_64-scei-ps4 -fsanitize=vptr %s 2>&1 | FileCheck -check-prefix=CHECK-SAN-WARN %s
-// RUN: %clang -### -c -target x86_64-scei-ps4 -fsanitize=vptr -frtti %s 2>&1 | FileCheck -check-prefix=CHECK-OK %s
-// RUN: %clang -### -c -target x86_64-scei-ps4 -fsanitize=vptr -fno-rtti %s 2>&1 | FileCheck -check-prefix=CHECK-SAN-ERROR %s
-// RUN: %clang -### -c -target x86_64-scei-ps4 -fsanitize=undefined %s 2>&1 | FileCheck -check-prefix=CHECK-SAN-WARN %s
-// RUN: %clang -### -c -target x86_64-scei-ps4 -fsanitize=undefined -frtti %s 2>&1 | FileCheck -check-prefix=CHECK-OK %s
-// RUN: %clang -### -c -target x86_64-scei-ps4 -fsanitize=undefined -fno-rtti %s 2>&1 | FileCheck -check-prefix=CHECK-SAN-ERROR %s
-// RUN: %clang -### -c -target x86_64-unknown-unknown -fsanitize=vptr %s 2>&1 | FileCheck -check-prefix=CHECK-OK %s
-// RUN: %clang -### -c -target x86_64-unknown-unknown -fsanitize=vptr -frtti %s 2>&1 | FileCheck -check-prefix=CHECK-OK %s
-// RUN: %clang -### -c -target x86_64-unknown-unknown -fsanitize=vptr -fno-rtti %s 2>&1 | FileCheck -check-prefix=CHECK-SAN-ERROR %s
-// RUN: %clang -### -c -target x86_64-unknown-unknown -fsanitize=undefined %s 2>&1 | FileCheck -check-prefix=CHECK-OK %s
-// RUN: %clang -### -c -target x86_64-unknown-unknown -fsanitize=undefined -frtti %s 2>&1 | FileCheck -check-prefix=CHECK-OK %s
-// RUN: %clang -### -c -target x86_64-unknown-unknown -fsanitize=undefined -fno-rtti %s 2>&1 | FileCheck -check-prefix=CHECK-SAN-ERROR %s
+// RUN: %clang -### -c -fsanitize=vptr -frtti %s 2>&1 | FileCheck -check-prefix=CHECK-OK -check-prefix=RTTI %s
+// RUN: %clang -### -c -fsanitize=vptr -fno-rtti %s 2>&1 | FileCheck -check-prefix=CHECK-SAN-ERROR %s
+// RUN: %clang -### -c -fsanitize=undefined -frtti %s 2>&1 | FileCheck -check-prefix=CHECK-OK -check-prefix=RTTI %s
+// RUN: %clang -### -c -fsanitize=undefined -fno-rtti %s 2>&1 | FileCheck -check-prefix=CHECK-SAN-ERROR %s
+
+// RUN: %clang -### -c -target x86_64-scei-ps4        -fsanitize=vptr %s 2>&1 | FileCheck -check-prefix=CHECK-SAN-WARN -check-prefix=RTTI %s
+// RUN: %clang -### -c -target x86_64-unknown-unknown -fsanitize=vptr %s 2>&1 | FileCheck -check-prefix=CHECK-OK -check-prefix=RTTI %s
+// RUN: %clang -### -c -target x86_64-scei-ps4        -fsanitize=undefined %s 2>&1 | FileCheck -check-prefix=CHECK-SAN-WARN -check-prefix=RTTI %s
+// RUN: %clang -### -c -target x86_64-unknown-unknown -fsanitize=undefined %s 2>&1 | FileCheck -check-prefix=CHECK-OK -check-prefix=RTTI %s
 
 // Exceptions + no/default rtti
-// RUN: %clang -### -c -target x86_64-scei-ps4 -fcxx-exceptions -fno-rtti %s 2>&1 | FileCheck -check-prefix=CHECK-EXC-ERROR-CXX %s
-// RUN: %clang -### -c -target x86_64-scei-ps4 -fcxx-exceptions %s 2>&1 | FileCheck -check-prefix=CHECK-EXC-WARN %s
-// RUN: %clang -### -c -target x86_64-unknown-unknown -fcxx-exceptions -fno-rtti %s 2>&1 | FileCheck -check-prefix=CHECK-OK %s
-// RUN: %clang -### -c -target x86_64-unknown-unknown -fcxx-exceptions %s 2>&1 | FileCheck -check-prefix=CHECK-OK %s
+// RUN: %clang -### -c -target x86_64-scei-ps4        -fcxx-exceptions -fno-rtti %s 2>&1 | FileCheck -check-prefix=CHECK-EXC-ERROR-CXX %s
+// RUN: %clang -### -c -target x86_64-unknown-unknown -fcxx-exceptions -fno-rtti %s 2>&1 | FileCheck -check-prefix=CHECK-OK -check-prefix=NO-RTTI %s
+// RUN: %clang -### -c -target x86_64-scei-ps4        -fcxx-exceptions %s 2>&1 | FileCheck -check-prefix=CHECK-EXC-WARN -check-prefix=RTTI %s
+// RUN: %clang -### -c -target x86_64-unknown-unknown -fcxx-exceptions %s 2>&1 | FileCheck -check-prefix=CHECK-OK -check-prefix=NO-RTTI %s
+
 // In C++, -fexceptions implies -fcxx-exceptions
-// RUN: %clang -x c++ -### -c -target x86_64-scei-ps4 -fexceptions -fno-rtti %s 2>&1 | FileCheck -check-prefix=CHECK-EXC-ERROR %s
-// RUN: %clang -x c++ -### -c -target x86_64-scei-ps4 -fexceptions %s 2>&1 | FileCheck -check-prefix=CHECK-EXC-WARN %s
-// RUN: %clang -x c++ -### -c -target x86_64-unknown-unknown -fexceptions -fno-rtti %s 2>&1 | FileCheck -check-prefix=CHECK-OK %s
-// RUN: %clang -x c++ -### -c -target x86_64-unknown-unknown -fexceptions %s 2>&1 | FileCheck -check-prefix=CHECK-OK %s
+// RUN: %clang -x c++ -### -c -target x86_64-scei-ps4        -fexceptions -fno-rtti %s 2>&1 | FileCheck -check-prefix=CHECK-EXC-ERROR %s
+// RUN: %clang -x c++ -### -c -target x86_64-unknown-unknown -fexceptions -fno-rtti %s 2>&1 | FileCheck -check-prefix=CHECK-OK -check-prefix=NO-RTTI %s
+// RUN: %clang -x c++ -### -c -target x86_64-scei-ps4        -fexceptions %s 2>&1 | FileCheck -check-prefix=CHECK-EXC-WARN -check-prefix=RTTI %s
+// RUN: %clang -x c++ -### -c -target x86_64-unknown-unknown -fexceptions %s 2>&1 | FileCheck -check-prefix=CHECK-OK -check-prefix=NO-RTTI %s
 
 // -frtti + exceptions
-// RUN: %clang -### -c -target x86_64-scei-ps4 -fcxx-exceptions -frtti %s 2>&1 | FileCheck -check-prefix=CHECK-OK %s
-// RUN: %clang -### -c -target x86_64-unknown-unknown -fcxx-exceptions -frtti %s 2>&1 | FileCheck -check-prefix=CHECK-OK %s
+// RUN: %clang -### -c -fcxx-exceptions -frtti %s 2>&1 | FileCheck -check-prefix=CHECK-OK %s
 
 // -f{no-,}rtti/default
-// RUN: %clang -### -c -target x86_64-scei-ps4 -frtti %s 2>&1 | FileCheck -check-prefix=CHECK-RTTI %s
-// RUN: %clang -### -c -target x86_64-scei-ps4 -fno-rtti %s 2>&1 | FileCheck -check-prefix=CHECK-NO-RTTI %s
-// RUN: %clang -### -c -target x86_64-scei-ps4 %s 2>&1 | FileCheck -check-prefix=CHECK-NO-RTTI %s
-// RUN: %clang -### -c -target x86_64-unknown-unknown -frtti %s 2>&1 | FileCheck -check-prefix=CHECK-RTTI %s
-// RUN: %clang -### -c -target x86_64-unknown-unknown -fno-rtti %s 2>&1 | FileCheck -check-prefix=CHECK-NO-RTTI %s
+// RUN: %clang -### -c -frtti %s 2>&1 | FileCheck -check-prefix=CHECK-RTTI %s
+// RUN: %clang -### -c -fno-rtti %s 2>&1 | FileCheck -check-prefix=CHECK-NO-RTTI %s
+
+// RUN: %clang -### -c -target x86_64-scei-ps4        %s 2>&1 | FileCheck -check-prefix=CHECK-NO-RTTI %s
 // RUN: %clang -### -c -target x86_64-unknown-unknown %s 2>&1 | FileCheck -check-prefix=CHECK-RTTI %s
 
-// CHECK-SAN-WARN: implicitly disabling vptr sanitizer because rtti wasn't enabled
+// CHECK-SAN-WARN: implicitly enabling rtti for the vptr sanitizer
 // CHECK-SAN-ERROR: invalid argument '-fsanitize=vptr' not allowed with '-fno-rtti'
 // CHECK-EXC-WARN: implicitly enabling rtti for exception handling
 // CHECK-EXC-ERROR: invalid argument '-fno-rtti' not allowed with '-fexceptions'