diff --git a/common_clang.cpp b/common_clang.cpp
index 982c9dd3..392a0e31 100644
--- a/common_clang.cpp
+++ b/common_clang.cpp
@@ -201,97 +201,94 @@ Compile(const char *pszProgramSource, const char **pInputHeaders,
   try {
     std::unique_ptr<OCLFEBinaryResult> pResult(new OCLFEBinaryResult());
 
-    // LLVM doesn't guarantee thread safety,
-    // therefore we serialize execution of LLVM code.
-    llvm::sys::SmartScopedLock<true> compileGuard {*compileMutex};
+    // Create the clang compiler
+    std::unique_ptr<clang::CompilerInstance> compiler(
+        new clang::CompilerInstance());
 
-    // Parse options
     CompileOptionsParser optionsParser(pszOpenCLVer);
-    optionsParser.processOptions(pszOptions, pszOptionsEx);
 
     // Prepare error log
     llvm::raw_string_ostream err_ostream(pResult->getLogRef());
-
-    // Prepare our diagnostic client.
-    llvm::IntrusiveRefCntPtr<clang::DiagnosticIDs> DiagID(
-        new clang::DiagnosticIDs());
-    llvm::IntrusiveRefCntPtr<clang::DiagnosticOptions> DiagOpts(
-        new clang::DiagnosticOptions());
-    DiagOpts->ShowPresumedLoc = true;
-    clang::TextDiagnosticPrinter *DiagsPrinter =
+    {
+      llvm::sys::SmartScopedLock<true> compileGuard {*compileMutex};
+
+      // Parse options
+      optionsParser.processOptions(pszOptions, pszOptionsEx);
+
+      // Prepare our diagnostic client.
+      llvm::IntrusiveRefCntPtr<clang::DiagnosticIDs> DiagID(
+          new clang::DiagnosticIDs());
+      llvm::IntrusiveRefCntPtr<clang::DiagnosticOptions> DiagOpts(
+          new clang::DiagnosticOptions());
+      DiagOpts->ShowPresumedLoc = true;
+      clang::TextDiagnosticPrinter *DiagsPrinter =
         new clang::TextDiagnosticPrinter(err_ostream, &*DiagOpts);
-    llvm::IntrusiveRefCntPtr<clang::DiagnosticsEngine> Diags(
-        new clang::DiagnosticsEngine(DiagID, &*DiagOpts, DiagsPrinter));
-
-    // Create the clang compiler
-    std::unique_ptr<clang::CompilerInstance> compiler(
-        new clang::CompilerInstance());
+      llvm::IntrusiveRefCntPtr<clang::DiagnosticsEngine> Diags(
+          new clang::DiagnosticsEngine(DiagID, &*DiagOpts, DiagsPrinter));
 
-    // Prepare output buffer
-    std::unique_ptr<llvm::raw_pwrite_stream>
+      // Prepare output buffer
+      std::unique_ptr<llvm::raw_pwrite_stream>
         ir_ostream(new llvm::raw_svector_ostream(pResult->getIRBufferRef()));
-    // Set buffers
-    // CompilerInstance takes ownership over output stream
-    compiler->setOutputStream(std::move(ir_ostream));
+      // Set buffers
+      // CompilerInstance takes ownership over output stream
+      compiler->setOutputStream(std::move(ir_ostream));
 
-    compiler->setDiagnostics(&*Diags);
+      compiler->setDiagnostics(&*Diags);
 
-    llvm::IntrusiveRefCntPtr<llvm::vfs::OverlayFileSystem> OverlayFS(
-        new llvm::vfs::OverlayFileSystem(llvm::vfs::getRealFileSystem()));
-    llvm::IntrusiveRefCntPtr<llvm::vfs::InMemoryFileSystem> MemFS(
-        new llvm::vfs::InMemoryFileSystem);
-    OverlayFS->pushOverlay(MemFS);
+      llvm::IntrusiveRefCntPtr<llvm::vfs::OverlayFileSystem> OverlayFS(
+          new llvm::vfs::OverlayFileSystem(llvm::vfs::getRealFileSystem()));
+      llvm::IntrusiveRefCntPtr<llvm::vfs::InMemoryFileSystem> MemFS(
+          new llvm::vfs::InMemoryFileSystem);
+      OverlayFS->pushOverlay(MemFS);
 
-    compiler->createFileManager(OverlayFS);
-    compiler->createSourceManager(compiler->getFileManager());
+      compiler->createFileManager(OverlayFS);
+      compiler->createSourceManager(compiler->getFileManager());
 
-    // Calling ResetAllOptionOccurrences as WA for issue from here:
-    // https://reviews.llvm.org/D66324?id=219733#1680231
-    llvm::cl::ResetAllOptionOccurrences();
-    // Create compiler invocation from user args before trickering with it
-    clang::CompilerInvocation::CreateFromArgs(compiler->getInvocation(),
-                                              optionsParser.args(), *Diags);
+      // Calling ResetAllOptionOccurrences as WA for issue from here:
+      // https://reviews.llvm.org/D66324?id=219733#1680231
+      llvm::cl::ResetAllOptionOccurrences();
+      // Create compiler invocation from user args before trickering with it
+      clang::CompilerInvocation::CreateFromArgs(compiler->getInvocation(),
+          optionsParser.args(), *Diags);
 
-    // Configure our handling of diagnostics.
-    ProcessWarningOptions(*Diags, compiler->getDiagnosticOpts());
+      // Configure our handling of diagnostics.
+      ProcessWarningOptions(*Diags, compiler->getDiagnosticOpts());
 
-    // Map memory buffers to a virtual file system
+      // Map memory buffers to a virtual file system
 
-    // Source file
-    MemFS->addFile(
-        optionsParser.getSourceName(), (time_t)0,
-        llvm::MemoryBuffer::getMemBuffer(
+      // Source file
+      MemFS->addFile(
+          optionsParser.getSourceName(), (time_t)0,
+          llvm::MemoryBuffer::getMemBuffer(
             llvm::StringRef(pszProgramSource), optionsParser.getSourceName()));
 
-    // Input header with OpenCL defines.
-    std::vector<Resource> vHeaderWithDefs;
-    if (!GetHeaders(vHeaderWithDefs)) {
-      return CL_COMPILE_PROGRAM_FAILURE;
-    }
+      // Input header with OpenCL defines.
+      std::vector<Resource> vHeaderWithDefs;
+      if (!GetHeaders(vHeaderWithDefs)) {
+        return CL_COMPILE_PROGRAM_FAILURE;
+      }
 
-    for (const auto &Header:vHeaderWithDefs) {
-      auto Buf = llvm::MemoryBuffer::getMemBuffer(
-          llvm::StringRef(Header.m_data, Header.m_size),
-          Header.m_name);
+      for (const auto &Header:vHeaderWithDefs) {
+        auto Buf = llvm::MemoryBuffer::getMemBuffer(
+            llvm::StringRef(Header.m_data, Header.m_size),
+            Header.m_name);
 
-      MemFS->addFile(Header.m_name,(time_t)0, std::move(Buf));
-    }
+        MemFS->addFile(Header.m_name,(time_t)0, std::move(Buf));
+      }
 
-    // Input Headers
-    for (unsigned int i = 0; i < uiNumInputHeaders; ++i) {
-      auto Header = llvm::MemoryBuffer::getMemBuffer(
-          pInputHeaders[i], pInputHeadersNames[i]);
-      MemFS->addFile(pInputHeadersNames[i], (time_t)0, std::move(Header));
+      // Input Headers
+      for (unsigned int i = 0; i < uiNumInputHeaders; ++i) {
+        auto Header = llvm::MemoryBuffer::getMemBuffer(
+            pInputHeaders[i], pInputHeadersNames[i]);
+        MemFS->addFile(pInputHeadersNames[i], (time_t)0, std::move(Header));
+      }
     }
-
-
     // Execute the frontend actions.
     bool success = false;
     try {
       success = clang::ExecuteCompilerInvocation(compiler.get());
     } catch (const std::exception &) {
     }
-
     pResult->setIRType(IR_TYPE_COMPILED_OBJECT);
     pResult->setIRName(optionsParser.getSourceName());
 
@@ -306,11 +303,11 @@ Compile(const char *pszProgramSource, const char **pInputHeaders,
     if (success && optionsParser.hasEmitSPIRV()) {
       // Translate LLVM IR to SPIR-V.
       llvm::StringRef LLVM_IR(static_cast<const char*>(pResult->GetIR()),
-                              pResult->GetIRSize());
+          pResult->GetIRSize());
       std::unique_ptr<llvm::MemoryBuffer> MB = llvm::MemoryBuffer::getMemBuffer(LLVM_IR, pResult->GetIRName(), false);
       llvm::LLVMContext Context;
       auto E = llvm::getOwningLazyBitcodeModule(std::move(MB), Context,
-                                               /*ShouldLazyLoadMetadata=*/true);
+          /*ShouldLazyLoadMetadata=*/true);
       llvm::logAllUnhandledErrors(E.takeError(), err_ostream, "error: ");
       std::unique_ptr<llvm::Module> M = std::move(*E);
 
@@ -334,9 +331,11 @@ Compile(const char *pszProgramSource, const char **pInputHeaders,
       err_ostream << Err.c_str();
       err_ostream.flush();
     }
-
-    if (pBinaryResult) {
-      *pBinaryResult = pResult.release();
+    {
+      llvm::sys::SmartScopedLock<true> compileGuard {*compileMutex};
+      if (pBinaryResult) {
+        *pBinaryResult = pResult.release();
+      }
     }
     return success ? CL_SUCCESS : CL_COMPILE_PROGRAM_FAILURE;
   } catch (std::bad_alloc &) {