diff --git a/include/swift/Remote/Failure.h b/include/swift/Remote/Failure.h
index d2a4b50ccce..8f00726ce24 100644
--- a/include/swift/Remote/Failure.h
+++ b/include/swift/Remote/Failure.h
@@ -318,14 +318,9 @@ template <> struct Failure::ArgTypesForFailureKind<Failure::KIND##_t> {  \
 };
 #include "swift/Remote/FailureKinds.def"
 
-template <>
-struct Failure::IsAcceptableArgType<Failure::ArgType_String, const char *> {
-  static constexpr bool value = true;
-};
-
-template <>
-struct Failure::IsAcceptableArgType<Failure::ArgType_String, std::string> {
-  static constexpr bool value = true;
+template <class T>
+struct Failure::IsAcceptableArgType<Failure::ArgType_String, T> {
+  static constexpr bool value = std::is_convertible<T, std::string>::value;
 };
 
 template <>
diff --git a/include/swift/Remote/FailureKinds.def b/include/swift/Remote/FailureKinds.def
index 27155f3bce8..c6cc10ec060 100644
--- a/include/swift/Remote/FailureKinds.def
+++ b/include/swift/Remote/FailureKinds.def
@@ -13,9 +13,16 @@
 // FAILURE(KIND, TEXT, ARGTYS)
 
 FAILURE(Unknown, "an unknown failure occurred", ())
+FAILURE(BadArgument, "the API was called with a bad argument", ())
+
 FAILURE(Memory, "an unknown failure occurred while reading %0 at address %1",
         (String, Address))
 
+FAILURE(DependentArgument,
+        "API was called with a dependent type", ())
+FAILURE(TypeHasNoSuchMember,
+        "type has no member named '%0'", (String))
+
 FAILURE(CouldNotResolveTypeDecl,
         "could not resolve a type with mangled name '%0'", (String))
 
diff --git a/include/swift/RemoteAST/RemoteAST.h b/include/swift/RemoteAST/RemoteAST.h
index 1ff3e0cd57b..5087f7694de 100644
--- a/include/swift/RemoteAST/RemoteAST.h
+++ b/include/swift/RemoteAST/RemoteAST.h
@@ -182,12 +182,22 @@ public:
   getDeclForRemoteNominalTypeDescriptor(remote::RemoteAddress address);
 
   /// Given a type in the local AST, try to resolve the offset of its
-  /// property with the given name.
+  /// member with the given name.  This supports:
   ///
-  /// This may fail by returning an empty optional.  Failure may indicate
-  /// that an offset for the property could not be resolved, or it may
-  /// simply indicate that the property has a non-zero offset.
-  Result<uint64_t> getOffsetForProperty(Type type, StringRef propertyName);
+  ///   - stored properties of structs
+  ///   - stored properties of classes
+  ///   - elements of tuples
+  ///
+  /// Failure may indicate that an offset for the property could not be
+  /// resolved, or it may simply indicate that the property is not laid
+  /// out at a known offset.
+  ///
+  /// If the caller has the address of type metadata for the type, it may
+  /// pass it in; this may allow the implementation to compute an offset in
+  /// situations where it otherwise cannot.
+  Result<uint64_t> getOffsetOfMember(Type type,
+                                     remote::RemoteAddress optMetadataAddress,
+                                     StringRef memberName);
 };
 
 } // end namespace remoteAST
diff --git a/lib/RemoteAST/RemoteAST.cpp b/lib/RemoteAST/RemoteAST.cpp
index ed7fc358a41..8a631b26708 100644
--- a/lib/RemoteAST/RemoteAST.cpp
+++ b/lib/RemoteAST/RemoteAST.cpp
@@ -617,8 +617,48 @@ public:
   getKindForRemoteTypeMetadata(RemoteAddress metadata) = 0;
   virtual Result<NominalTypeDecl*>
   getDeclForRemoteNominalTypeDescriptor(RemoteAddress descriptor) = 0;
-  virtual Result<uint64_t>
-  getOffsetForProperty(Type type, StringRef propertyName) = 0;
+
+  Result<uint64_t>
+  getOffsetOfMember(Type type, RemoteAddress optMetadata, StringRef memberName){
+    // Sanity check: obviously invalid arguments.
+    if (!type || memberName.empty())
+      return Result<uint64_t>::emplaceFailure(Failure::BadArgument);
+
+    // Sanity check: if the caller gave us a dependent type, there's no way
+    // we can handle that.
+    if (type->hasTypeParameter() || type->hasArchetype())
+      return Result<uint64_t>::emplaceFailure(Failure::DependentArgument);
+
+    // Split into cases.
+    if (auto typeDecl = type->getNominalOrBoundGenericNominal()) {
+      return getOffsetOfMember(type, typeDecl, optMetadata, memberName);
+    } else if (auto tupleType = type->getAs<TupleType>()) {
+      return getOffsetOfMember(tupleType, optMetadata, memberName);
+    } else {
+      return Result<uint64_t>::emplaceFailure(Failure::TypeHasNoSuchMember,
+                                              memberName);
+    }
+  }
+
+  Result<uint64_t>
+  getOffsetOfMember(Type type, NominalTypeDecl *typeDecl,
+                    RemoteAddress optMetadata, StringRef memberName) {
+    // FIXME
+    return Result<uint64_t>::emplaceFailure(Failure::Unknown);
+  }
+
+  Result<uint64_t>
+  getOffsetOfMember(TupleType *type, RemoteAddress optMetadata,
+                    StringRef memberName) {
+    // Check that the member "name" is a valid index into the tuple.
+    unsigned index;
+    if (memberName.getAsInteger(10, index) || index >= type->getNumElements())
+      return Result<uint64_t>::emplaceFailure(Failure::TypeHasNoSuchMember,
+                                              memberName);
+
+    // FIXME
+    return Result<uint64_t>::emplaceFailure(Failure::Unknown);
+  }
 };
 
 /// A template for generating concrete implementations of the
@@ -660,12 +700,6 @@ public:
     return getBuilder().template getFailureAsResult<NominalTypeDecl*>(
              Failure::Unknown);
   }
-
-  Result<uint64_t>
-  getOffsetForProperty(Type type, StringRef propertyName) override {
-    // TODO
-    return Result<uint64_t>::emplaceFailure(Failure::Unknown);
-  }
 };
 
 } // end anonymous namespace
@@ -713,6 +747,7 @@ RemoteASTContext::getDeclForRemoteNominalTypeDescriptor(RemoteAddress address) {
 }
 
 Result<uint64_t>
-RemoteASTContext::getOffsetForProperty(Type type, StringRef propertyName) {
-  return asImpl(Impl)->getOffsetForProperty(type, propertyName);
+RemoteASTContext::getOffsetOfMember(Type type, RemoteAddress optMetadata,
+                                    StringRef memberName) {
+  return asImpl(Impl)->getOffsetOfMember(type, optMetadata, memberName);
 }