diff --git a/include/clang/Basic/Builtins.def b/include/clang/Basic/Builtins.def
index 4d51503..af22810 100644
--- a/include/clang/Basic/Builtins.def
+++ b/include/clang/Basic/Builtins.def
@@ -35,6 +35,7 @@
 //  a -> __builtin_va_list
 //  A -> "reference" to __builtin_va_list
 //  V -> Vector, following num elements and a base type.
+//  X -> _Complex, followed by the base type.
 //  P -> FILE
 //  J -> jmp_buf
 //  SJ -> sigjmp_buf
@@ -163,6 +164,64 @@
 BUILTIN(__builtin_tanhl, "LdLd", "nc")
 BUILTIN(__builtin_tanl, "LdLd", "nc")
 
+// C99 complex builtins
+BUILTIN(__builtin_cabs, "dXd", "Fnc")
+BUILTIN(__builtin_cabsf, "fXf", "Fnc")
+BUILTIN(__builtin_cabsl, "LdXLd", "Fnc")
+BUILTIN(__builtin_cacos, "XdXd", "Fnc")
+BUILTIN(__builtin_cacosf, "XfXf", "Fnc")
+BUILTIN(__builtin_cacosl, "XLdXLd", "Fnc")
+BUILTIN(__builtin_carg, "dXd", "Fnc")
+BUILTIN(__builtin_cargf, "fXf", "Fnc")
+BUILTIN(__builtin_cargl, "LdXLd", "Fnc")
+BUILTIN(__builtin_casin, "XdXd", "Fnc")
+BUILTIN(__builtin_casinf, "XfXf", "Fnc")
+BUILTIN(__builtin_casinl, "XLdXLd", "Fnc")
+BUILTIN(__builtin_catan, "XdXd", "Fnc")
+BUILTIN(__builtin_catanf, "XfXf", "Fnc")
+BUILTIN(__builtin_catanl, "XLdXLd", "Fnc")
+BUILTIN(__builtin_ccos, "XdXd", "Fnc")
+BUILTIN(__builtin_ccosf, "XfXf", "Fnc")
+BUILTIN(__builtin_ccosl, "XLdXLd", "Fnc")
+BUILTIN(__builtin_ccosh, "XdXd", "Fnc")
+BUILTIN(__builtin_ccoshf, "XfXf", "Fnc")
+BUILTIN(__builtin_ccoshl, "XLdXLd", "Fnc")
+BUILTIN(__builtin_cexp, "XdXd", "Fnc")
+BUILTIN(__builtin_cexpf, "XfXf", "Fnc")
+BUILTIN(__builtin_cexpl, "XLdXLd", "Fnc")
+BUILTIN(__builtin_cimag, "dXd", "Fnc")
+BUILTIN(__builtin_cimagf, "fXf", "Fnc")
+BUILTIN(__builtin_cimagl, "LdXLd", "Fnc")
+BUILTIN(__builtin_conj, "dXd", "Fnc")
+BUILTIN(__builtin_conjf, "fXf", "Fnc")
+BUILTIN(__builtin_conjl, "LdXLd", "Fnc")
+BUILTIN(__builtin_clog, "XdXd", "Fnc")
+BUILTIN(__builtin_clogf, "XfXf", "Fnc")
+BUILTIN(__builtin_clogl, "XLdXLd", "Fnc")
+BUILTIN(__builtin_cproj, "XdXd", "Fnc")
+BUILTIN(__builtin_cprojf, "XfXf", "Fnc")
+BUILTIN(__builtin_cprojl, "XLdXLd", "Fnc")
+BUILTIN(__builtin_cpow, "XdXdXd", "Fnc")
+BUILTIN(__builtin_cpowf, "XfXfXf", "Fnc")
+BUILTIN(__builtin_cpowl, "XLdXLdXLd", "Fnc")
+BUILTIN(__builtin_creal, "dXd", "Fnc")
+BUILTIN(__builtin_crealf, "fXf", "Fnc")
+BUILTIN(__builtin_creall, "LdXLd", "Fnc")
+BUILTIN(__builtin_csin, "XdXd", "Fnc")
+BUILTIN(__builtin_csinf, "XfXf", "Fnc")
+BUILTIN(__builtin_csinl, "XLdXLd", "Fnc")
+BUILTIN(__builtin_csinh, "XdXd", "Fnc")
+BUILTIN(__builtin_csinhf, "XfXf", "Fnc")
+BUILTIN(__builtin_csinhl, "XLdXLd", "Fnc")
+BUILTIN(__builtin_csqrt, "XdXd", "Fnc")
+BUILTIN(__builtin_csqrtf, "XfXf", "Fnc")
+BUILTIN(__builtin_csqrtl, "XLdXLd", "Fnc")
+BUILTIN(__builtin_ctan, "XdXd", "Fnc")
+BUILTIN(__builtin_ctanf, "XfXf", "Fnc")
+BUILTIN(__builtin_ctanl, "XLdXLd", "Fnc")
+BUILTIN(__builtin_ctanh, "XdXd", "Fnc")
+BUILTIN(__builtin_ctanhf, "XfXf", "Fnc")
+BUILTIN(__builtin_ctanhl, "XLdXLd", "Fnc")
 
 // FP Comparisons.
 BUILTIN(__builtin_isgreater     , "i.", "nc")
diff --git a/lib/AST/ASTContext.cpp b/lib/AST/ASTContext.cpp
index 48d1ce9..e0223b0 100644
--- a/lib/AST/ASTContext.cpp
+++ b/lib/AST/ASTContext.cpp
@@ -4118,6 +4118,11 @@
     Type = Context.getVectorType(ElementType, NumElements);
     break;
   }
+  case 'X': {
+    QualType ElementType = DecodeTypeFromStr(Str, Context, Error, false);
+    Type = Context.getComplexType(ElementType);
+    break;
+  }      
   case 'P':
     Type = Context.getFILEType();
     if (Type.isNull()) {