diff --git a/reactos/tools/rbuild/module.cpp b/reactos/tools/rbuild/module.cpp
index f6e6341c268..e35cfd3a631 100644
--- a/reactos/tools/rbuild/module.cpp
+++ b/reactos/tools/rbuild/module.cpp
@@ -1509,19 +1509,27 @@ If::ProcessXML()
 Property::Property ( const XMLElement& node_,
                      const Project& project_,
                      const Module* module_ )
-	: node(node_), project(project_), module(module_)
+	: project(project_), module(module_)
 {
 	const XMLAttribute* att;
 
-	att = node.GetAttribute ( "name", true );
+	att = node_.GetAttribute ( "name", true );
 	assert(att);
 	name = att->value;
 
-	att = node.GetAttribute ( "value", true );
+	att = node_.GetAttribute ( "value", true );
 	assert(att);
 	value = att->value;
 }
 
+Property::Property ( const Project& project_,
+                     const Module* module_,
+                     const std::string& name_,
+                     const std::string& value_ )
+	: project(project_), module(module_), name(name_), value(value_)
+{
+}
+
 void
 Property::ProcessXML()
 {
diff --git a/reactos/tools/rbuild/project.cpp b/reactos/tools/rbuild/project.cpp
index d68d4ac5eb6..5b961ffc960 100644
--- a/reactos/tools/rbuild/project.cpp
+++ b/reactos/tools/rbuild/project.cpp
@@ -103,13 +103,29 @@ FileLocation::FileLocation ( Directory* directory,
 
 
 Project::Project ( const Configuration& configuration,
-                   const string& filename )
+                   const string& filename,
+                   const std::map<std::string, std::string>* properties )
 	: xmlfile (filename),
 	  node (NULL),
 	  head (NULL),
 	  configuration (configuration)
 {
 	_backend = NULL;
+
+	if ( properties )
+	{
+		std::map<string, string>::const_iterator it;
+		for (it = properties->begin (); it != properties->end (); it++)
+		{
+			const Property *existing = LookupProperty( it->first );
+			if ( !existing )
+			{
+				Property* property = new Property ( *this, NULL, it->first, it->second );
+				non_if_data.properties.push_back (property );
+			}
+		}
+	}
+
 	ReadXml();
 }
 
diff --git a/reactos/tools/rbuild/rbuild.cpp b/reactos/tools/rbuild/rbuild.cpp
index abe255ff038..cc84f40d1ff 100644
--- a/reactos/tools/rbuild/rbuild.cpp
+++ b/reactos/tools/rbuild/rbuild.cpp
@@ -35,6 +35,7 @@ using std::vector;
 static string BuildSystem;
 static string RootXmlFile;
 static Configuration configuration;
+static std::map<string, string> properties;
 
 bool
 ParseAutomaticDependencySwitch (
@@ -167,6 +168,28 @@ ParseProxyMakefileSwitch ( char switchChar2 )
 	return true;
 }
 
+bool
+ParseDefineSwitch ( char* switchStart )
+{
+	string s = string ( switchStart + 2 );
+	string::size_type separator =  s.find ( '=' );
+	if ( separator == string::npos || separator == 0 )
+	{
+		printf ( "Invalid define switch: '%s'\n", switchStart );
+		return false;
+	}
+	if ( s.find ( '=', separator + 1 ) != string::npos )
+	{
+		printf ( "Invalid define switch: '%s'\n", switchStart );
+		return false;
+	}
+
+	string var = s.substr ( 0, separator );
+	string val = s.substr ( separator + 1 );
+	properties.insert ( std::pair<string, string> ( var, val ) );
+	return true;
+}
+
 bool
 ParseSwitch ( int argc, char** argv, int index )
 {
@@ -202,6 +225,8 @@ ParseSwitch ( int argc, char** argv, int index )
 			return ParseMakeSwitch ( switchChar2 );
 		case 'p':
 			return ParseProxyMakefileSwitch ( switchChar2 );
+		case 'D':
+			return ParseDefineSwitch ( argv[index] );
 		default:
 			printf (
 				"Unknown switch -%c\n",
@@ -253,6 +278,7 @@ main ( int argc, char** argv )
 		printf ( "                tree.\n" );
 		printf ( "  -vs{version}  Version of MS VS project files. Default is %s.\n", MS_VS_DEF_VERSION );
 		printf ( "  -vo{version|configuration} Adds subdirectory path to the default Intermediate-Outputdirectory.\n" );
+		printf ( "  -Dvar=val     Set the value of 'var' variable to 'val'.\n" );
 		printf ( "\n" );
 		printf ( "  buildsystem   Target build system. Can be one of:\n" );
 
@@ -272,7 +298,7 @@ main ( int argc, char** argv )
 		string projectFilename ( RootXmlFile );
 
 		printf ( "Reading build files..." );
-		Project project ( configuration, projectFilename );
+		Project project ( configuration, projectFilename, &properties );
 		printf ( "done\n" );
 
 		project.SetBackend ( Backend::Factory::Create (
diff --git a/reactos/tools/rbuild/rbuild.h b/reactos/tools/rbuild/rbuild.h
index 5476dab2715..d84969a553c 100644
--- a/reactos/tools/rbuild/rbuild.h
+++ b/reactos/tools/rbuild/rbuild.h
@@ -215,7 +215,8 @@ public:
 	IfableData non_if_data;
 
 	Project ( const Configuration& configuration,
-	          const std::string& filename );
+	          const std::string& filename,
+	          const std::map<std::string, std::string>* properties = NULL );
 	~Project ();
 	void SetBackend ( Backend* backend ) { _backend = backend; }
 	Backend& GetBackend() { return *_backend; }
@@ -590,7 +591,6 @@ public:
 class Property
 {
 public:
-	const XMLElement& node;
 	const Project& project;
 	const Module* module;
 	std::string name, value;
@@ -599,6 +599,11 @@ public:
 	           const Project& project_,
 	           const Module* module_ );
 
+	Property ( const Project& project_,
+	           const Module* module_,
+	           const std::string& name_,
+	           const std::string& value_ );
+
 	void ProcessXML();
 };