Index: cfe/trunk/docs/ReleaseNotes.rst
===================================================================
--- cfe/trunk/docs/ReleaseNotes.rst
+++ cfe/trunk/docs/ReleaseNotes.rst
@@ -60,6 +60,16 @@
 
 The option ....
 
+Deprecated Compiler Flags
+-------------------------
+
+The following options are deprecated and ignored. They will be removed in
+future versions of Clang.
+
+- -fslp-vectorize-aggressive used to enable the BB vectorizing pass. They have been superseeded
+  by the normal SLP vectorizer.
+- -fno-slp-vectorize-aggressive used to be the default behavior of clang.
+
 New Pragmas in Clang
 -----------------------
 
Index: cfe/trunk/include/clang/Basic/DiagnosticDriverKinds.td
===================================================================
--- cfe/trunk/include/clang/Basic/DiagnosticDriverKinds.td
+++ cfe/trunk/include/clang/Basic/DiagnosticDriverKinds.td
@@ -178,6 +178,8 @@
   InGroup<InvalidCommandLineArgument>;
 def warn_ignored_gcc_optimization : Warning<"optimization flag '%0' is not supported">,
   InGroup<IgnoredOptimizationArgument>;
+def warn_ignored_clang_option : Warning<"the flag '%0' has been deprecated and will be ignored">,
+  InGroup<UnusedCommandLineArgument>;
 def warn_drv_unsupported_opt_for_target : Warning<
   "optimization flag '%0' is not supported for target '%1'">,
   InGroup<IgnoredOptimizationArgument>;
Index: cfe/trunk/include/clang/Driver/Options.td
===================================================================
--- cfe/trunk/include/clang/Driver/Options.td
+++ cfe/trunk/include/clang/Driver/Options.td
@@ -194,6 +194,16 @@
 def clang_ignored_m_Group : OptionGroup<"<clang ignored m group>">,
   Group<m_Group>, Flags<[Ignored]>;
 
+// Group for clang options in the process of deprecation.
+// Please include the version that deprecated the flag as comment to allow
+// easier garbage collection.
+def clang_ignored_legacy_options_Group : OptionGroup<"<clang legacy flags>">,
+  Group<f_Group>, Flags<[Ignored]>;
+
+// Retired with clang-5.0
+def : Flag<["-"], "fslp-vectorize-aggressive">, Group<clang_ignored_legacy_options_Group>;
+def : Flag<["-"], "fno-slp-vectorize-aggressive">, Group<clang_ignored_legacy_options_Group>;
+
 // Group that ignores all gcc optimizations that won't be implemented
 def clang_ignored_gcc_optimization_f_Group : OptionGroup<
   "<clang_ignored_gcc_optimization_f_Group>">, Group<f_Group>, Flags<[Ignored]>;
Index: cfe/trunk/lib/Driver/ToolChains/Clang.cpp
===================================================================
--- cfe/trunk/lib/Driver/ToolChains/Clang.cpp
+++ cfe/trunk/lib/Driver/ToolChains/Clang.cpp
@@ -2974,6 +2974,12 @@
     A->claim();
   }
 
+  for (const Arg *A :
+       Args.filtered(options::OPT_clang_ignored_legacy_options_Group)) {
+    D.Diag(diag::warn_ignored_clang_option) << A->getAsString(Args);
+    A->claim();
+  }
+
   claimNoWarnArgs(Args);
 
   Args.AddAllArgs(CmdArgs, options::OPT_R_Group);
Index: cfe/trunk/test/Driver/clang_f_opts.c
===================================================================
--- cfe/trunk/test/Driver/clang_f_opts.c
+++ cfe/trunk/test/Driver/clang_f_opts.c
@@ -356,6 +356,8 @@
 // RUN: -ftree-vrp                                                            \
 // RUN: -fno-devirtualize                                                     \
 // RUN: -fno-devirtualize-speculatively                                       \
+// RUN: -fslp-vectorize-aggressive                                            \
+// RUN: -fno-slp-vectorize-aggressive                                         \
 // RUN: %s 2>&1 | FileCheck --check-prefix=CHECK-WARNING %s
 // CHECK-WARNING-DAG: optimization flag '-finline-limit=1000' is not supported
 // CHECK-WARNING-DAG: optimization flag '-finline-limit' is not supported
@@ -422,6 +424,8 @@
 // CHECK-WARNING-DAG: optimization flag '-ftree-vrp' is not supported
 // CHECK-WARNING-DAG: optimization flag '-fno-devirtualize' is not supported
 // CHECK-WARNING-DAG: optimization flag '-fno-devirtualize-speculatively' is not supported
+// CHECK-WARNING-DAG: the flag '-fslp-vectorize-aggressive' has been deprecated and will be ignored
+// CHECK-WARNING-DAG: the flag '-fno-slp-vectorize-aggressive' has been deprecated and will be ignored
 
 // Test that we mute the warning on these
 // RUN: %clang -### -finline-limit=1000 -Wno-invalid-command-line-argument              \