Index: include/clang/ASTMatchers/ASTMatchers.h
===================================================================
--- include/clang/ASTMatchers/ASTMatchers.h
+++ include/clang/ASTMatchers/ASTMatchers.h
@@ -167,6 +167,21 @@
 ///   matches "typedef int X"
 const internal::VariadicDynCastAllOfMatcher<Decl, TypedefDecl> typedefDecl;
 
+/// \brief Matches the underlying type of a typedef declaration
+///
+/// Given
+/// \code
+///   typedef int X;
+///   typedef float Y;
+/// \endcode
+/// typedefDecl(hasUnderlyingType(asString("int")))
+///   matches "typedef int X"
+AST_MATCHER_P(TypedefDecl, hasUnderlyingType, internal::Matcher<QualType>,
+              InnerMatcher) {
+  QualType UnderlyingType = Node.getUnderlyingType();
+  return InnerMatcher.matches(UnderlyingType, Finder, Builder);
+}
+
 /// \brief Matches AST nodes that were expanded within the main-file.
 ///
 /// Example matches X but not Y (matcher = recordDecl(isExpansionInMainFile())
Index: lib/ASTMatchers/Dynamic/Registry.cpp
===================================================================
--- lib/ASTMatchers/Dynamic/Registry.cpp
+++ lib/ASTMatchers/Dynamic/Registry.cpp
@@ -223,6 +223,7 @@
   REGISTER_MATCHER(hasTrueExpression);
   REGISTER_MATCHER(hasTypeLoc);
   REGISTER_MATCHER(hasUnaryOperand);
+  REGISTER_MATCHER(hasUnderlyingType);
   REGISTER_MATCHER(hasValueType);
   REGISTER_MATCHER(ifStmt);
   REGISTER_MATCHER(ignoringImpCasts);