diff --git a/common.py b/common.py
old mode 100644
new mode 100755
index be3e9526..2a788722
--- a/common.py
+++ b/common.py
@@ -121,4 +121,7 @@ def check_tools(m):
                         if int(t11[j])<input_tools[t][0][j]:
                             error(input_tools[t][2], m)
                             ret = 0
+                            break
+                        if int(t11[j])>input_tools[t][0][j]:
+                            break
     return ret
diff --git a/opt.cpp b/opt.cpp
index ff7ee410..f70e522d 100644
--- a/opt.cpp
+++ b/opt.cpp
@@ -514,11 +514,31 @@ Optimize(llvm::Module *module, int optLevel) {
         llvm::initializeInstrumentation(*registry);
         llvm::initializeTarget(*registry);
 
-        optPM.add(llvm::createGlobalDCEPass(), 200);
+        optPM.add(llvm::createGlobalDCEPass(), 185);
+
+        // Setup to use LLVM default AliasAnalysis
+        // Ideally, we want call:
+        //    llvm::PassManagerBuilder pm_Builder;
+        //    pm_Builder.OptLevel = optLevel;
+        //    pm_Builder.addInitialAliasAnalysisPasses(optPM);
+        // but the addInitialAliasAnalysisPasses() is a private function
+        // so we explicitly enable them here.
+        // Need to keep sync with future LLVM change
+        // An alternative is to call populateFunctionPassManager()
+        optPM.add(llvm::createTypeBasedAliasAnalysisPass(), 190);
+        optPM.add(llvm::createBasicAliasAnalysisPass());
+        optPM.add(llvm::createCFGSimplificationPass());
+        // Here clang has an experimental pass SROAPass instead of
+        // ScalarReplAggregatesPass. We should add it in the future.
+        optPM.add(llvm::createScalarReplAggregatesPass());
+        optPM.add(llvm::createEarlyCSEPass());
+        optPM.add(llvm::createLowerExpectIntrinsicPass());
+        optPM.add(llvm::createTypeBasedAliasAnalysisPass());
+        optPM.add(llvm::createBasicAliasAnalysisPass());
 
         // Early optimizations to try to reduce the total amount of code to
         // work with if we can
-        optPM.add(llvm::createReassociatePass());
+        optPM.add(llvm::createReassociatePass(), 200);
         optPM.add(llvm::createConstantPropagationPass());
         optPM.add(llvm::createDeadInstEliminationPass());
         optPM.add(llvm::createCFGSimplificationPass());