diff --git a/src/parser/cxx/ast.h b/src/parser/cxx/ast.h
index 8532e880..92e9d11e 100644
--- a/src/parser/cxx/ast.h
+++ b/src/parser/cxx/ast.h
@@ -1640,6 +1640,7 @@ class BuiltinOffsetofExpressionAST final : public ExpressionAST {
   SourceLocation commaLoc;
   ExpressionAST* expression = nullptr;
   SourceLocation rparenLoc;
+  FieldSymbol* symbol = nullptr;
 
   void accept(ASTVisitor* visitor) override { visitor->visit(this); }
 
@@ -3156,6 +3157,7 @@ class EnumSpecifierAST final : public SpecifierAST {
   SourceLocation commaLoc;
   List<EnumeratorAST*>* enumeratorList = nullptr;
   SourceLocation rbraceLoc;
+  Symbol* symbol = nullptr;
 
   void accept(ASTVisitor* visitor) override { visitor->visit(this); }
 
diff --git a/src/parser/cxx/const_expression_evaluator.cc b/src/parser/cxx/const_expression_evaluator.cc
index f44bc447..193add8e 100644
--- a/src/parser/cxx/const_expression_evaluator.cc
+++ b/src/parser/cxx/const_expression_evaluator.cc
@@ -32,6 +32,7 @@
 #include <cxx/types.h>
 
 #include <format>
+#include <optional>
 
 namespace cxx {
 
@@ -214,6 +215,7 @@ auto ConstExpressionEvaluator::operator()(BuiltinBitCastExpressionAST* ast)
 
 auto ConstExpressionEvaluator::operator()(BuiltinOffsetofExpressionAST* ast)
     -> std::optional<ConstValue> {
+  if (ast->symbol) return ast->symbol->offset();
   return std::nullopt;
 }
 
diff --git a/src/parser/cxx/memory_layout.cc b/src/parser/cxx/memory_layout.cc
index 551c82af..92746dfd 100644
--- a/src/parser/cxx/memory_layout.cc
+++ b/src/parser/cxx/memory_layout.cc
@@ -242,8 +242,13 @@ struct SizeOf {
 struct AlignmentOf {
   const MemoryLayout& memoryLayout;
 
+  auto operator()(const ClassType* type) const -> std::optional<std::size_t> {
+    return type->symbol()->alignment();
+  }
+
   auto operator()(auto type) const -> std::optional<std::size_t> {
     // ### TODO
+    if (!type) return std::nullopt;
     return memoryLayout.sizeOf(type);
   }
 };
@@ -297,11 +302,13 @@ void MemoryLayout::setSizeOfLongDouble(std::size_t sizeOfLongDouble) {
 
 auto MemoryLayout::sizeOf(const Type* type) const
     -> std::optional<std::size_t> {
+  if (!type) return std::nullopt;
   return visit(SizeOf{*this}, type);
 }
 
 auto MemoryLayout::alignmentOf(const Type* type) const
     -> std::optional<std::size_t> {
+  if (!type) return std::nullopt;
   return visit(AlignmentOf{*this}, type);
 }
 
diff --git a/src/parser/cxx/name_lookup.h b/src/parser/cxx/name_lookup.h
index a64ce5ee..4bf82190 100644
--- a/src/parser/cxx/name_lookup.h
+++ b/src/parser/cxx/name_lookup.h
@@ -49,12 +49,12 @@ class Lookup {
   [[nodiscard]] auto lookupType(NestedNameSpecifierAST* nestedNameSpecifier,
                                 const Identifier* id) const -> Symbol*;
 
- private:
-  [[nodiscard]] auto unqualifiedLookup(const Name* name) const -> Symbol*;
-
   [[nodiscard]] auto qualifiedLookup(Scope* scope, const Name* name) const
       -> Symbol*;
 
+ private:
+  [[nodiscard]] auto unqualifiedLookup(const Name* name) const -> Symbol*;
+
   [[nodiscard]] auto qualifiedLookup(Symbol* scopedSymbol,
                                      const Name* name) const -> Symbol*;
 
diff --git a/src/parser/cxx/parser.cc b/src/parser/cxx/parser.cc
index 17fd5e83..7f8c5da6 100644
--- a/src/parser/cxx/parser.cc
+++ b/src/parser/cxx/parser.cc
@@ -25,6 +25,7 @@
 #include <cxx/const_expression_evaluator.h>
 #include <cxx/control.h>
 #include <cxx/literals.h>
+#include <cxx/memory_layout.h>
 #include <cxx/name_lookup.h>
 #include <cxx/name_printer.h>
 #include <cxx/names.h>
@@ -34,6 +35,7 @@
 #include <cxx/token.h>
 #include <cxx/type_printer.h>
 #include <cxx/types.h>
+#include <cxx/util.h>
 #include <cxx/views/symbol_chain.h>
 
 #include <algorithm>
@@ -42,12 +44,6 @@
 #include <ranges>
 #include <unordered_set>
 
-#include "cxx/cxx_fwd.h"
-#include "cxx/parser_fwd.h"
-#include "cxx/source_location.h"
-#include "cxx/symbols_fwd.h"
-#include "cxx/token_fwd.h"
-
 namespace cxx {
 
 namespace {
@@ -2652,6 +2648,19 @@ auto Parser::parse_builtin_offsetof_expression(ExpressionAST*& yyast,
   parse_expression(ast->expression, ctx);
   expect(TokenKind::T_RPAREN, ast->rparenLoc);
 
+  auto classType = type_cast<ClassType>(ast->typeId->type);
+  auto id = ast_cast<IdExpressionAST>(ast->expression);
+
+  if (classType && id && !id->nestedNameSpecifier) {
+    auto symbol = classType->symbol();
+    auto name = convertName(id->unqualifiedId);
+    auto member = Lookup{scope_}.qualifiedLookup(symbol->scope(), name);
+    auto field = symbol_cast<FieldSymbol>(member);
+    ast->symbol = field;
+  }
+
+  ast->type = control_->getSizeType();
+
   return true;
 }
 
@@ -5631,7 +5640,10 @@ auto Parser::parse_defining_type_specifier(
     if (parse_enum_specifier(yyast, specs)) {
       lookahead.commit();
 
+      auto enumSpec = ast_cast<EnumSpecifierAST>(yyast);
+
       specs.setTypeSpecifier(yyast);
+      specs.type = enumSpec->symbol->type();
 
       return true;
     }
@@ -5641,6 +5653,7 @@ auto Parser::parse_defining_type_specifier(
       lookahead.commit();
 
       specs.setTypeSpecifier(classSpecifier);
+      specs.type = classSpecifier->symbol->type();
       yyast = classSpecifier;
 
       return true;
@@ -6867,6 +6880,7 @@ auto Parser::parse_elaborated_type_specifier(
   }
 
   ast->symbol = classSymbol;
+  specs.type = classSymbol->type();
 
   return true;
 }
@@ -7971,6 +7985,7 @@ auto Parser::parse_enum_specifier(SpecifierAST*& yyast, DeclSpecs& specs)
   ast->colonLoc = colonLoc;
   ast->typeSpecifierList = typeSpecifierList;
   ast->lbraceLoc = lbraceLoc;
+  ast->symbol = symbol;
 
   if (!match(TokenKind::T_RBRACE, ast->rbraceLoc)) {
     parse_enumerator_list(ast->enumeratorList, symbol->type());
@@ -9416,7 +9431,69 @@ auto Parser::parse_class_specifier(
     expect(TokenKind::T_RBRACE, ast->rbraceLoc);
   }
 
-  ast->symbol->setComplete(true);
+  if (!is_template(classSymbol)) {
+    int offset = 0;
+    int alignment = 1;
+
+    for (auto base : classSymbol->baseClasses()) {
+      auto baseClassSymbol = symbol_cast<ClassSymbol>(base->symbol());
+
+      if (!baseClassSymbol) {
+        if (config_.checkTypes) {
+          parse_error(base->location(), std::format("base class '{}' not found",
+                                                    to_string(base->name())));
+        }
+        continue;
+      }
+
+      offset = align_to(offset, baseClassSymbol->alignment());
+      offset += baseClassSymbol->sizeInBytes();
+      alignment = std::max(alignment, baseClassSymbol->alignment());
+    }
+
+    for (auto member : classSymbol->scope()->symbols()) {
+      auto field = symbol_cast<FieldSymbol>(member);
+      if (!field) continue;
+      if (field->isStatic()) continue;
+
+      if (!field->alignment()) {
+        if (config_.checkTypes) {
+          parse_error(field->location(),
+                      std::format("alignment of incomplete type '{}'",
+                                  to_string(field->type(), field->name())));
+        }
+        continue;
+      }
+
+      auto size = control_->memoryLayout()->sizeOf(field->type());
+
+      if (!size.has_value()) {
+        if (config_.checkTypes) {
+          parse_error(field->location(),
+                      std::format("size of incomplete type '{}'",
+                                  to_string(field->type(), field->name())));
+        }
+        continue;
+      }
+
+      if (classSymbol->isUnion()) {
+        offset = std::max(offset, int(size.value()));
+      } else {
+        offset = align_to(offset, field->alignment());
+        field->setOffset(offset);
+        offset += size.value();
+      }
+
+      alignment = std::max(alignment, field->alignment());
+    }
+
+    offset = align_to(offset, alignment);
+
+    classSymbol->setAlignment(alignment);
+    classSymbol->setSizeInBytes(offset);
+  }
+
+  classSymbol->setComplete(true);
 
   return true;
 }
@@ -9798,6 +9875,9 @@ auto Parser::declareField(DeclaratorAST* declarator, const Decl& decl)
   applySpecifiers(fieldSymbol, decl.specs);
   fieldSymbol->setName(name);
   fieldSymbol->setType(type);
+  if (auto alignment = control_->memoryLayout()->alignmentOf(type)) {
+    fieldSymbol->setAlignment(alignment.value());
+  }
   scope_->addSymbol(fieldSymbol);
   return fieldSymbol;
 }
diff --git a/src/parser/cxx/symbols.cc b/src/parser/cxx/symbols.cc
index 1146344a..84fdc67c 100644
--- a/src/parser/cxx/symbols.cc
+++ b/src/parser/cxx/symbols.cc
@@ -178,7 +178,15 @@ auto ClassSymbol::isComplete() const -> bool { return isComplete_; }
 
 void ClassSymbol::setComplete(bool isComplete) { isComplete_ = isComplete; }
 
-auto ClassSymbol::sizeInBytes() const -> std::size_t { return sizeInBytes_; }
+auto ClassSymbol::sizeInBytes() const -> int { return sizeInBytes_; }
+
+void ClassSymbol::setSizeInBytes(int sizeInBytes) {
+  sizeInBytes_ = sizeInBytes;
+}
+
+auto ClassSymbol::alignment() const -> int { return alignment_; }
+
+void ClassSymbol::setAlignment(int alignment) { alignment_ = alignment; }
 
 auto ClassSymbol::hasBaseClass(Symbol* symbol) const -> bool {
   std::unordered_set<const ClassSymbol*> processed;
@@ -493,6 +501,14 @@ auto FieldSymbol::isInline() const -> bool { return isInline_; }
 
 void FieldSymbol::setInline(bool isInline) { isInline_ = isInline; }
 
+auto FieldSymbol::offset() const -> int { return offset_; }
+
+void FieldSymbol::setOffset(int offset) { offset_ = offset; }
+
+auto FieldSymbol::alignment() const -> int { return alignment_; }
+
+void FieldSymbol::setAlignment(int alignment) { alignment_ = alignment; }
+
 ParameterSymbol::ParameterSymbol(Scope* enclosingScope)
     : Symbol(Kind, enclosingScope) {}
 
diff --git a/src/parser/cxx/symbols.h b/src/parser/cxx/symbols.h
index d2b96331..bb6c4cb2 100644
--- a/src/parser/cxx/symbols.h
+++ b/src/parser/cxx/symbols.h
@@ -251,7 +251,11 @@ class ClassSymbol final : public ScopedSymbol {
   [[nodiscard]] auto isComplete() const -> bool;
   void setComplete(bool isComplete);
 
-  [[nodiscard]] auto sizeInBytes() const -> std::size_t;
+  [[nodiscard]] auto sizeInBytes() const -> int;
+  void setSizeInBytes(int sizeInBytes);
+
+  [[nodiscard]] auto alignment() const -> int;
+  void setAlignment(int alignment);
 
   [[nodiscard]] auto hasBaseClass(Symbol* symbol) const -> bool;
 
@@ -305,7 +309,8 @@ class ClassSymbol final : public ScopedSymbol {
   std::unique_ptr<TemplateInfo<ClassSymbol>> templateInfo_;
   ClassSymbol* templateClass_ = nullptr;
   std::size_t templateSepcializationIndex_ = 0;
-  std::size_t sizeInBytes_ = 0;
+  int sizeInBytes_ = 0;
+  int alignment_ = 0;
   union {
     std::uint32_t flags_{};
     struct {
@@ -566,6 +571,12 @@ class FieldSymbol final : public Symbol {
   [[nodiscard]] auto isInline() const -> bool;
   void setInline(bool isInline);
 
+  [[nodiscard]] auto offset() const -> int;
+  void setOffset(int offset);
+
+  [[nodiscard]] auto alignment() const -> int;
+  void setAlignment(int alignment);
+
  private:
   union {
     std::uint32_t flags_{};
@@ -577,6 +588,8 @@ class FieldSymbol final : public Symbol {
       std::uint32_t isInline_ : 1;
     };
   };
+  int offset_{};
+  int alignment_{};
 };
 
 class ParameterSymbol final : public Symbol {
diff --git a/tests/unit_tests/sema/wasm_stdlib_01.cc b/tests/unit_tests/sema/wasm_stdlib_01.cc
new file mode 100644
index 00000000..238d9fdf
--- /dev/null
+++ b/tests/unit_tests/sema/wasm_stdlib_01.cc
@@ -0,0 +1,6 @@
+// RUN: %cxx -toolchain wasm32 -ftemplates -fcheck %s
+
+#include <cctype>
+#include <cstdio>
+#include <cstdlib>
+#include <cstring>