diff --git a/source/binary.cpp b/source/binary.cpp
index c8b7c38c2..689937f02 100644
--- a/source/binary.cpp
+++ b/source/binary.cpp
@@ -20,13 +20,14 @@
 #include <iterator>
 #include <limits>
 #include <unordered_map>
+#include <vector>
 
 #include "assembly_grammar.h"
 #include "diagnostic.h"
 #include "ext_inst.h"
 #include "opcode.h"
 #include "operand.h"
-#include "spirv-tools/libspirv.h"
+#include "spirv/1.1/spirv.h"
 #include "spirv_constant.h"
 #include "spirv_endian.h"
 
diff --git a/source/binary.h b/source/binary.h
index dd48258fa..375e0105b 100644
--- a/source/binary.h
+++ b/source/binary.h
@@ -16,7 +16,6 @@
 #define LIBSPIRV_BINARY_H_
 
 #include "spirv-tools/libspirv.h"
-#include "spirv/1.1/spirv.h"
 #include "spirv_definition.h"
 
 // Functions
diff --git a/source/diagnostic.h b/source/diagnostic.h
index 72d537aed..78f9a5b65 100644
--- a/source/diagnostic.h
+++ b/source/diagnostic.h
@@ -16,7 +16,7 @@
 #define LIBSPIRV_DIAGNOSTIC_H_
 
 #include <sstream>
-#include <utility>
+#include <string>
 
 #include "spirv-tools/libspirv.hpp"
 
diff --git a/source/libspirv.cpp b/source/libspirv.cpp
index 9afb9cb1d..02e87ea5e 100644
--- a/source/libspirv.cpp
+++ b/source/libspirv.cpp
@@ -14,7 +14,6 @@
 
 #include "spirv-tools/libspirv.hpp"
 
-#include "message.h"
 #include "table.h"
 
 namespace spvtools {
diff --git a/source/message.h b/source/message.h
index 1489090b8..60f5d5632 100644
--- a/source/message.h
+++ b/source/message.h
@@ -17,7 +17,7 @@
 
 #include <string>
 
-#include "spirv-tools/libspirv.hpp"
+#include "spirv-tools/libspirv.h"
 
 namespace spvtools {
 
diff --git a/source/opt/build_module.h b/source/opt/build_module.h
index 1dc2c11ab..d396a3a9e 100644
--- a/source/opt/build_module.h
+++ b/source/opt/build_module.h
@@ -17,7 +17,6 @@
 
 #include <memory>
 #include <string>
-#include <vector>
 
 #include "module.h"
 #include "spirv-tools/libspirv.hpp"
diff --git a/source/opt/constants.h b/source/opt/constants.h
index 24574fc92..d6199e8f4 100644
--- a/source/opt/constants.h
+++ b/source/opt/constants.h
@@ -15,8 +15,8 @@
 #ifndef LIBSPIRV_OPT_CONSTANTS_H_
 #define LIBSPIRV_OPT_CONSTANTS_H_
 
-#include <cassert>
 #include <memory>
+#include <utility>
 #include <vector>
 
 #include "make_unique.h"
diff --git a/source/opt/def_use_manager.cpp b/source/opt/def_use_manager.cpp
index 19178ebfa..2d0e79a57 100644
--- a/source/opt/def_use_manager.cpp
+++ b/source/opt/def_use_manager.cpp
@@ -14,11 +14,7 @@
 
 #include "def_use_manager.h"
 
-#include <functional>
-
-#include "instruction.h"
 #include "log.h"
-#include "module.h"
 #include "reflect.h"
 
 namespace spvtools {
diff --git a/source/opt/def_use_manager.h b/source/opt/def_use_manager.h
index 41c405a5f..cd779d533 100644
--- a/source/opt/def_use_manager.h
+++ b/source/opt/def_use_manager.h
@@ -17,12 +17,11 @@
 
 #include <list>
 #include <unordered_map>
-#include <utility>
 #include <vector>
 
 #include "instruction.h"
-#include "message.h"
 #include "module.h"
+#include "spirv-tools/libspirv.hpp"
 
 namespace spvtools {
 namespace opt {
diff --git a/source/opt/fold_spec_constant_op_and_composite_pass.cpp b/source/opt/fold_spec_constant_op_and_composite_pass.cpp
index 0170dcb0d..84248146a 100644
--- a/source/opt/fold_spec_constant_op_and_composite_pass.cpp
+++ b/source/opt/fold_spec_constant_op_and_composite_pass.cpp
@@ -14,10 +14,9 @@
 
 #include "fold_spec_constant_op_and_composite_pass.h"
 
+#include <algorithm>
 #include <initializer_list>
-#include <memory>
 #include <tuple>
-#include <unordered_map>
 
 #include "constants.h"
 #include "make_unique.h"
@@ -249,6 +248,20 @@ FoldSpecConstantOpAndCompositePass::FoldSpecConstantOpAndCompositePass()
       type_mgr_(nullptr),
       id_to_const_val_() {}
 
+Pass::Status FoldSpecConstantOpAndCompositePass::Process(ir::Module* module) {
+  Initialize(module);
+  return ProcessImpl(module);
+}
+
+void FoldSpecConstantOpAndCompositePass::Initialize(ir::Module* module) {
+  type_mgr_.reset(new analysis::TypeManager(consumer(), *module));
+  def_use_mgr_.reset(new analysis::DefUseManager(consumer(), module));
+  for (const auto& id_def : def_use_mgr_->id_to_defs()) {
+    max_id_ = std::max(max_id_, id_def.first);
+  }
+  module_ = module;
+};
+
 Pass::Status FoldSpecConstantOpAndCompositePass::ProcessImpl(
     ir::Module* module) {
   bool modified = false;
diff --git a/source/opt/fold_spec_constant_op_and_composite_pass.h b/source/opt/fold_spec_constant_op_and_composite_pass.h
index 8bca3e559..6e2eea109 100644
--- a/source/opt/fold_spec_constant_op_and_composite_pass.h
+++ b/source/opt/fold_spec_constant_op_and_composite_pass.h
@@ -15,7 +15,6 @@
 #ifndef LIBSPIRV_OPT_FOLD_SPEC_CONSTANT_OP_AND_COMPOSITE_PASS_H_
 #define LIBSPIRV_OPT_FOLD_SPEC_CONSTANT_OP_AND_COMPOSITE_PASS_H_
 
-#include <algorithm>
 #include <memory>
 #include <unordered_map>
 #include <vector>
@@ -35,22 +34,13 @@ class FoldSpecConstantOpAndCompositePass : public Pass {
   FoldSpecConstantOpAndCompositePass();
 
   const char* name() const override { return "fold-spec-const-op-composite"; }
-  Status Process(ir::Module* module) override {
-    Initialize(module);
-    return ProcessImpl(module);
-  };
+
+  Status Process(ir::Module* module) override;
 
  private:
   // Initializes the type manager, def-use manager and get the maximal id used
   // in the module.
-  void Initialize(ir::Module* module) {
-    type_mgr_.reset(new analysis::TypeManager(consumer(), *module));
-    def_use_mgr_.reset(new analysis::DefUseManager(consumer(), module));
-    for (const auto& id_def : def_use_mgr_->id_to_defs()) {
-      max_id_ = std::max(max_id_, id_def.first);
-    }
-    module_ = module;
-  };
+  void Initialize(ir::Module* module);
 
   // The real entry of processing. Iterates through the types-constants-globals
   // section of the given module, finds the Spec Constants defined with
diff --git a/source/opt/instruction.cpp b/source/opt/instruction.cpp
index 40e2951aa..bccac1211 100644
--- a/source/opt/instruction.cpp
+++ b/source/opt/instruction.cpp
@@ -14,7 +14,6 @@
 
 #include "instruction.h"
 
-#include <cassert>
 #include <initializer_list>
 
 #include "reflect.h"
diff --git a/source/opt/ir_loader.h b/source/opt/ir_loader.h
index c5c735996..bcb55f1e3 100644
--- a/source/opt/ir_loader.h
+++ b/source/opt/ir_loader.h
@@ -19,9 +19,8 @@
 
 #include "basic_block.h"
 #include "instruction.h"
-#include "message.h"
 #include "module.h"
-#include "spirv-tools/libspirv.h"
+#include "spirv-tools/libspirv.hpp"
 
 namespace spvtools {
 namespace ir {
diff --git a/source/opt/iterator.h b/source/opt/iterator.h
index ba25feae1..0430638ca 100644
--- a/source/opt/iterator.h
+++ b/source/opt/iterator.h
@@ -15,6 +15,7 @@
 #ifndef LIBSPIRV_OPT_ITERATOR_H_
 #define LIBSPIRV_OPT_ITERATOR_H_
 
+#include <cstddef>  // for ptrdiff_t
 #include <iterator>
 #include <memory>
 #include <type_traits>
@@ -29,10 +30,9 @@ namespace ir {
 // std::vector<|ValueType|>.
 template <typename ValueType, bool IsConst = false>
 class UptrVectorIterator
-    : public std::iterator<
-          std::random_access_iterator_tag,
-          typename std::conditional<IsConst, const ValueType, ValueType>::type,
-          ptrdiff_t> {
+    : public std::iterator<std::random_access_iterator_tag,
+                           typename std::conditional<IsConst, const ValueType,
+                                                     ValueType>::type> {
  public:
   using super = std::iterator<
       std::random_access_iterator_tag,
diff --git a/source/opt/log.h b/source/opt/log.h
index 0d5ce4b9a..717a3625a 100644
--- a/source/opt/log.h
+++ b/source/opt/log.h
@@ -20,7 +20,7 @@
 #include <utility>
 #include <vector>
 
-#include "message.h"
+#include "spirv-tools/libspirv.hpp"
 
 // Asserts the given condition is true. Otherwise, sends a message to the
 // consumer and exits the problem with failure code. Accepts the following
diff --git a/source/opt/pass.h b/source/opt/pass.h
index 7449bc11e..6e5df74d4 100644
--- a/source/opt/pass.h
+++ b/source/opt/pass.h
@@ -15,10 +15,10 @@
 #ifndef LIBSPIRV_OPT_PASS_H_
 #define LIBSPIRV_OPT_PASS_H_
 
-#include <memory>
+#include <utility>
 
-#include "message.h"
 #include "module.h"
+#include "spirv-tools/libspirv.hpp"
 
 namespace spvtools {
 namespace opt {
diff --git a/source/opt/pass_manager.h b/source/opt/pass_manager.h
index e1bdc7aaf..0bf29f7ae 100644
--- a/source/opt/pass_manager.h
+++ b/source/opt/pass_manager.h
@@ -19,10 +19,11 @@
 #include <vector>
 
 #include "log.h"
-#include "message.h"
 #include "module.h"
 #include "pass.h"
 
+#include "spirv-tools/libspirv.hpp"
+
 namespace spvtools {
 namespace opt {
 
diff --git a/source/opt/set_spec_constant_default_value_pass.cpp b/source/opt/set_spec_constant_default_value_pass.cpp
index 2e9f36fe7..d49e2f156 100644
--- a/source/opt/set_spec_constant_default_value_pass.cpp
+++ b/source/opt/set_spec_constant_default_value_pass.cpp
@@ -16,18 +16,15 @@
 
 #include <cctype>
 #include <cstring>
-#include <string>
 #include <tuple>
-#include <unordered_map>
 #include <vector>
 
-#include "spirv-tools/libspirv.h"
-#include "util/parse_number.h"
-
 #include "def_use_manager.h"
 #include "make_unique.h"
+#include "spirv-tools/libspirv.h"
 #include "type_manager.h"
 #include "types.h"
+#include "util/parse_number.h"
 
 namespace spvtools {
 namespace opt {
diff --git a/source/opt/type_manager.cpp b/source/opt/type_manager.cpp
index ce4b6764b..ed8a13c78 100644
--- a/source/opt/type_manager.cpp
+++ b/source/opt/type_manager.cpp
@@ -12,11 +12,12 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-#include <algorithm>
+#include "type_manager.h"
+
+#include <utility>
 
 #include "log.h"
 #include "reflect.h"
-#include "type_manager.h"
 
 namespace spvtools {
 namespace opt {
diff --git a/source/opt/type_manager.h b/source/opt/type_manager.h
index 48fa21223..fa04d8082 100644
--- a/source/opt/type_manager.h
+++ b/source/opt/type_manager.h
@@ -18,9 +18,10 @@
 #include <memory>
 #include <unordered_map>
 #include <unordered_set>
+#include <vector>
 
-#include "message.h"
 #include "module.h"
+#include "spirv-tools/libspirv.hpp"
 #include "types.h"
 
 namespace spvtools {
diff --git a/source/table.cpp b/source/table.cpp
index 24ab52056..8f8580245 100644
--- a/source/table.cpp
+++ b/source/table.cpp
@@ -14,7 +14,7 @@
 
 #include "table.h"
 
-#include <cstdlib>
+#include <utility>
 
 spv_context spvContextCreate(spv_target_env env) {
   switch (env) {
diff --git a/source/table.h b/source/table.h
index 6b8631345..4b2158705 100644
--- a/source/table.h
+++ b/source/table.h
@@ -19,7 +19,7 @@
 
 #include "enum_set.h"
 #include "message.h"
-#include "spirv-tools/libspirv.h"
+#include "spirv-tools/libspirv.hpp"
 
 namespace libspirv {