Index: include/clang/Driver/CC1Options.td
===================================================================
--- include/clang/Driver/CC1Options.td
+++ include/clang/Driver/CC1Options.td
@@ -235,6 +235,10 @@
   HelpText<"Run the Loop vectorization passes">;
 def vectorize_slp : Flag<["-"], "vectorize-slp">,
   HelpText<"Run the SLP vectorization passes">;
+def proactive_loop_fusion : Flag<["-"], "proactive-loop-fusion">,
+  HelpText<"Run the Loop fusion passes">;
+def proactive_loop_fusion_analysis : Flag<["-"], "proactive-loop-fusion-analysis">,
+  HelpText<"Run the Loop fusion call graph passes">;
 def vectorize_slp_aggressive : Flag<["-"], "vectorize-slp-aggressive">,
   HelpText<"Run the BB vectorization passes">;
 def dependent_lib : Joined<["--"], "dependent-lib=">,
Index: include/clang/Driver/Options.td
===================================================================
--- include/clang/Driver/Options.td
+++ include/clang/Driver/Options.td
@@ -907,6 +907,14 @@
 def foperator_arrow_depth_EQ : Joined<["-"], "foperator-arrow-depth=">,
                                Group<f_Group>;
 def ftest_coverage : Flag<["-"], "ftest-coverage">, Group<f_Group>;
+
+def fproactive_loop_fusion : Flag<["-"], "fproactive-loop-fusion">, Group<f_Group>,
+  HelpText<"Enable the loop fusion passes">;
+def fno_proactive_loop_fusion : Flag<["-"], "fno-proactive-loop-fusion">, Group<f_Group>;
+def fproactive_loop_fusion_analysis : Flag<["-"], "fproactive-loop-fusion-analysis">, Group<f_Group>,
+  HelpText<"Enable the loop fusion analysis passes">;
+def fno_proactive_loop_fusion_analysis : Flag<["-"], "fno-proactive-loop-fusion analysis">, Group<f_Group>;
+
 def fvectorize : Flag<["-"], "fvectorize">, Group<f_Group>,
   HelpText<"Enable the loop vectorization passes">;
 def fno_vectorize : Flag<["-"], "fno-vectorize">, Group<f_Group>;
Index: include/clang/Frontend/CodeGenOptions.def
===================================================================
--- include/clang/Frontend/CodeGenOptions.def
+++ include/clang/Frontend/CodeGenOptions.def
@@ -124,6 +124,8 @@
 CODEGENOPT(VectorizeBB       , 1, 0) ///< Run basic block vectorizer.
 CODEGENOPT(VectorizeLoop     , 1, 0) ///< Run loop vectorizer.
 CODEGENOPT(VectorizeSLP      , 1, 0) ///< Run SLP vectorizer.
+CODEGENOPT(ProactiveLoopFusion, 1, 0) ///< Run proactive loop fusion.
+CODEGENOPT(ProactiveLoopFusionAnalysis, 1, 0) ///< Run proactive loop fusion analysis.
 
   /// Attempt to use register sized accesses to bit-fields in structures, when
   /// possible.
Index: lib/CodeGen/BackendUtil.cpp
===================================================================
--- lib/CodeGen/BackendUtil.cpp
+++ lib/CodeGen/BackendUtil.cpp
@@ -263,12 +263,16 @@
   PMBuilder.BBVectorize = CodeGenOpts.VectorizeBB;
   PMBuilder.SLPVectorize = CodeGenOpts.VectorizeSLP;
   PMBuilder.LoopVectorize = CodeGenOpts.VectorizeLoop;
+  PMBuilder.ProactiveLoopFusion = CodeGenOpts.ProactiveLoopFusion;
+  PMBuilder.ProactiveLoopFusionAnalysis = CodeGenOpts.ProactiveLoopFusionAnalysis;
 
   PMBuilder.DisableTailCalls = CodeGenOpts.DisableTailCalls;
   PMBuilder.DisableUnitAtATime = !CodeGenOpts.UnitAtATime;
   PMBuilder.DisableUnrollLoops = !CodeGenOpts.UnrollLoops;
   PMBuilder.MergeFunctions = CodeGenOpts.MergeFunctions;
   PMBuilder.RerollLoops = CodeGenOpts.RerollLoops;
+  PMBuilder.ProactiveLoopFusionAnalysis = CodeGenOpts.ProactiveLoopFusionAnalysis;
+  PMBuilder.ProactiveLoopFusion = CodeGenOpts.ProactiveLoopFusion;
 
   PMBuilder.addExtension(PassManagerBuilder::EP_EarlyAsPossible,
                          addAddDiscriminatorsPass);
Index: lib/Driver/Tools.cpp
===================================================================
--- lib/Driver/Tools.cpp
+++ lib/Driver/Tools.cpp
@@ -4334,9 +4334,19 @@
   bool EnableSLPVec = shouldEnableVectorizerAtOLevel(Args, true);
   OptSpecifier SLPVectAliasOption = EnableSLPVec ? options::OPT_O_Group :
     options::OPT_fslp_vectorize;
+
   if (Args.hasFlag(options::OPT_fslp_vectorize, SLPVectAliasOption,
                    options::OPT_fno_slp_vectorize, EnableSLPVec))
     CmdArgs.push_back("-vectorize-slp");
+  if (Args.hasFlag(options::OPT_fproactive_loop_fusion_analysis,
+                   options::OPT_fno_proactive_loop_fusion_analysis,false)) {
+    CmdArgs.push_back("-proactive-loop-fusion-analysis");
+  }
+
+  if (Args.hasFlag(options::OPT_fproactive_loop_fusion,
+                   options::OPT_fno_proactive_loop_fusion,false)) {
+    CmdArgs.push_back("-proactive-loop-fusion");
+  }
 
   // -fno-slp-vectorize-aggressive is default.
   if (Args.hasFlag(options::OPT_fslp_vectorize_aggressive,
@@ -6680,6 +6690,18 @@
   if (D.IsUsingLTO(Args))
     AddGoldPlugin(ToolChain, Args, CmdArgs);
 
+  if (D.IsUsingLTO(Args)) {
+    if (Args.hasFlag(options::OPT_fproactive_loop_fusion_analysis,
+                     options::OPT_fno_proactive_loop_fusion_analysis,false)) {
+      CmdArgs.push_back("-plugin-opt=proactive-loop-fusion-analysis");
+    }
+
+    if (Args.hasFlag(options::OPT_fproactive_loop_fusion,
+                     options::OPT_fno_proactive_loop_fusion,false)) {
+      CmdArgs.push_back("-plugin-opt=proactive-loop-fusion");
+    }
+  }
+
   bool NeedsSanitizerDeps = addSanitizerRuntimes(ToolChain, Args, CmdArgs);
   AddLinkerInputs(ToolChain, Inputs, Args, CmdArgs);
 
@@ -7511,6 +7533,18 @@
   if (D.IsUsingLTO(Args))
     AddGoldPlugin(ToolChain, Args, CmdArgs);
 
+  if (D.IsUsingLTO(Args)) {
+    if (Args.hasFlag(options::OPT_fproactive_loop_fusion_analysis,
+                     options::OPT_fno_proactive_loop_fusion_analysis,false)) {
+      CmdArgs.push_back("-plugin-opt=proactive-loop-fusion-analysis");
+    }
+
+    if (Args.hasFlag(options::OPT_fproactive_loop_fusion,
+                     options::OPT_fno_proactive_loop_fusion,false)) {
+      CmdArgs.push_back("-plugin-opt=proactive-loop-fusion");
+    }
+  }
+
   if (Args.hasArg(options::OPT_Z_Xlinker__no_demangle))
     CmdArgs.push_back("--no-demangle");
 
Index: lib/Frontend/CompilerInvocation.cpp
===================================================================
--- lib/Frontend/CompilerInvocation.cpp
+++ lib/Frontend/CompilerInvocation.cpp
@@ -477,6 +477,8 @@
   Opts.VectorizeBB = Args.hasArg(OPT_vectorize_slp_aggressive);
   Opts.VectorizeLoop = Args.hasArg(OPT_vectorize_loops);
   Opts.VectorizeSLP = Args.hasArg(OPT_vectorize_slp);
+  Opts.ProactiveLoopFusion = Args.hasArg(OPT_proactive_loop_fusion);
+  Opts.ProactiveLoopFusionAnalysis = Args.hasArg(OPT_proactive_loop_fusion_analysis);
 
   Opts.MainFileName = Args.getLastArgValue(OPT_main_file_name);
   Opts.VerifyModule = !Args.hasArg(OPT_disable_llvm_verifier);