Index: test/SemaCXX/attr-print.cpp
===================================================================
--- test/SemaCXX/attr-print.cpp
+++ test/SemaCXX/attr-print.cpp
@@ -34,3 +34,27 @@
   // CHECK: void callableWhen() __attribute__((callable_when("unconsumed", "consumed")));
   void callableWhen()  __attribute__((callable_when("unconsumed", "consumed")));
 };
+
+// CHECK: class __single_inheritance SingleInheritance;
+class __single_inheritance SingleInheritance;
+
+// CHECK: void sentinel(int a, ...) __attribute__((sentinel));
+void sentinel(int a, ...) __attribute__((sentinel));
+
+// CHECK: void sentinel_1n(int a, ...) __attribute__((sentinel(1)));
+void sentinel_1n(int a, ...) __attribute__((sentinel(1)));
+
+// CHECK: void sentinel_1d2n(int a, ...) __attribute__((sentinel(0, 1)));
+void sentinel_1d2n(int a, ...) __attribute__((sentinel(0, 1)));
+
+// CHECK: void sentinel_1n2n(int a, ...) __attribute__((sentinel(1, 1)));
+void sentinel_1n2n(int a, ...) __attribute__((sentinel(1, 1)));
+
+// It would be better if we didn't lose arguments in the following cases, but
+// at least the default values have the same semantics.
+
+// CHECK: void sentinel_1d(int a, ...) __attribute__((sentinel));
+void sentinel_1d(int a, ...) __attribute__((sentinel(0)));
+
+// CHECK: void sentinel_1d2d(int a, ...) __attribute__((sentinel));
+void sentinel_1d2d(int a, ...) __attribute__((sentinel(0, 0)));
Index: utils/TableGen/ClangAttrEmitter.cpp
===================================================================
--- utils/TableGen/ClangAttrEmitter.cpp
+++ utils/TableGen/ClangAttrEmitter.cpp
@@ -374,6 +374,11 @@
         OS << Default;
       OS << ";";
     }
+
+    std::string getIsOmitted() const override {
+      return "Default" + getUpperName().str() + " == get" +
+             getUpperName().str() + "()";
+    }
   };
 
   class StringArgument : public Argument {
@@ -1432,6 +1437,7 @@
       unsigned NonFakeArgs = 0;
       unsigned TrailingOptArgs = 0;
       bool FoundNonOptArg = false;
+      std::string Indent = "    ";
       for (const auto &arg : llvm::reverse(Args)) {
         if (arg->isFake())
           continue;
@@ -1446,9 +1452,14 @@
         }
         if (!TrailingOptArgs++)
           OS << "\";\n"
-             << "    unsigned TrailingOmittedArgs = 0;\n";
-        OS << "    if (" << arg->getIsOmitted() << ")\n"
-           << "      ++TrailingOmittedArgs;\n";
+             << Indent << "unsigned TrailingOmittedArgs = 0;\n";
+        OS << Indent << "if (" << arg->getIsOmitted() << ") {\n";
+        Indent += "  ";
+        OS << Indent << "++TrailingOmittedArgs;\n";
+      }
+      for (unsigned i = 0; i < TrailingOptArgs; ++i) {
+        Indent.resize(Indent.size() - 2);
+        OS << Indent << "}\n";
       }
       if (TrailingOptArgs)
         OS << "    OS << \"";
@@ -1463,26 +1474,21 @@
       for (const auto &arg : Args) {
         if (arg->isFake())
           continue;
-        if (ArgIndex) {
-          if (ArgIndex >= NonFakeArgs - TrailingOptArgs)
-            OS << "\";\n"
-               << "    if (" << ArgIndex << " < " << NonFakeArgs
-               << " - TrailingOmittedArgs)\n"
-               << "      OS << \", \";\n"
-               << "    OS << \"";
-          else
-            OS << ", ";
-        }
-        std::string IsOmitted = arg->getIsOmitted();
-        if (arg->isOptional() && IsOmitted != "false")
+        if (ArgIndex >= NonFakeArgs - TrailingOptArgs) {
           OS << "\";\n"
-             << "    if (!(" << IsOmitted << ")) {\n"
-             << "      OS << \"";
+             << "    if (" << ArgIndex << " < " << NonFakeArgs
+             << " - TrailingOmittedArgs) {\n";
+          if (ArgIndex)
+            OS << "      OS << \", \";\n";
+          OS << "      OS << \"";
+        } else if (ArgIndex)
+          OS << ", ";
         arg->writeValue(OS);
-        if (arg->isOptional() && IsOmitted != "false")
+        if (ArgIndex >= NonFakeArgs - TrailingOptArgs) {
           OS << "\";\n"
              << "    }\n"
              << "    OS << \"";
+        }
         ++ArgIndex;
       }
       if (TrailingOptArgs < NonFakeArgs)