diff --git a/source/app.d b/source/app.d
index 62faea9..a0e9cb4 100644
--- a/source/app.d
+++ b/source/app.d
@@ -193,11 +193,6 @@
 				auto settings = dub.getBuildSettings(build_platform, build_config);
 				settings.addDFlags(["-w", "-property"]);
 				settings.addVersions(getPackagesAsVersion(dub));
-
-				compiler.prepareBuildSettings(settings, BuildSetting.commandLine);
-				flags ~= settings.dflags;
-				flags ~= (mainsrc).toNativeString();
-
 				string dflags = environment.get("DFLAGS");
 				if( dflags ){
 					build_type = "$DFLAGS";
@@ -212,12 +207,17 @@
 						case "docs": assert(false, "docgen not implemented");
 					}
 				}
+				settings.addDFlags(dflags.split());
+
+				compiler.prepareBuildSettings(settings, BuildSetting.commandLine);
+				flags ~= settings.dflags;
+				flags ~= (mainsrc).toNativeString();
 
 				if( build_config.length ) logInfo("Building configuration "~build_config~", build type "~build_type);
 				else logInfo("Building default configuration, build type "~build_type);
 
-				logInfo("Running %s", "rdmd " ~ dflags ~ " " ~ join(flags, " "));
-				auto rdmd_pid = spawnProcess("rdmd " ~ dflags ~ " " ~ join(flags, " "));
+				logInfo("Running %s", "rdmd " ~ join(flags, " "));
+				auto rdmd_pid = spawnProcess("rdmd", flags);
 				auto result = rdmd_pid.wait();
 				enforce(result == 0, "Build command failed with exit code "~to!string(result));
 
diff --git a/source/dub/compilers/gdc.d b/source/dub/compilers/gdc.d
new file mode 100644
index 0000000..01aad25
--- /dev/null
+++ b/source/dub/compilers/gdc.d
@@ -0,0 +1,120 @@
+/**
+	GDC compiler support.
+
+	Copyright: © 2013 rejectedsoftware e.K.
+	License: Subject to the terms of the MIT license, as written in the included LICENSE.txt file.
+	Authors: Sönke Ludwig
+*/
+module dub.compilers.gdc;
+
+import dub.compilers.compiler;
+
+import std.algorithm;
+import std.array;
+import std.conv;
+import std.exception;
+import stdx.process;
+import vibe.core.log;
+
+
+class GdcCompiler : Compiler {
+	@property string name() const { return "gdc"; }
+
+	void prepareBuildSettings(ref BuildSettings settings, BuildSetting fields = BuildSetting.all)
+	{
+		// convert common DMD flags to the corresponding GDC flags
+		string[] newdflags;
+		foreach(f; settings.dflags){
+			switch(f){
+				default: newdflags ~= f; break;
+				case "-cov": newdflags ~= ["-fprofile-arcs", "-ftest-coverage"]; break;
+				case "-D": newdflags ~= "-fdoc"; break;
+				//case "-Dd[dir]": newdflags ~= ""; break;
+				//case "-Df[file]": newdflags ~= ""; break;
+				case "-d": newdflags ~= "-fdeprecated"; break;
+				case "-dw": break;
+				case "-de": break;
+				case "-debug": newdflags ~= "-fdebug"; break;
+				//case "-debug=[level/ident]": newdflags ~= ""; break;
+				//case "-debuglib=[ident]": newdflags ~= ""; break;
+				//case "-defaultlib=[ident]": newdflags ~= ""; break;
+				//case "-deps=[file]": newdflags ~= ""; break;
+				case "-fPIC": newdflags ~= ""; break;
+				case "-g": newdflags ~= "-g"; break;
+				case "-gc": newdflags ~= ["-g" ~ "-fdebug-c"]; break;
+				case "-gs": break;
+				case "-H": newdflags ~= "-fintfc"; break;
+				//case "-Hd[dir]": newdflags ~= ""; break;
+				//case "-Hf[file]": newdflags ~= ""; break;
+				case "-ignore": newdflags ~= "-fignore-unknown-pragmas"; break;
+				case "-inline": newdflags ~= "-finline-functions"; break;
+				//case "-lib": newdflags ~= ""; break;
+				//case "-m32": newdflags ~= ""; break;
+				//case "-m64": newdflags ~= ""; break;
+				case "-noboundscheck": newdflags ~= "-fno-bounds-check"; break;
+				case "-O": newdflags ~= "-O3"; break;
+				case "-o-": newdflags ~= "-fsyntax-only"; break;
+				//case "-od[dir]": newdflags ~= ""; break;
+				//case "-of[file]": newdflags ~= ""; break;
+				//case "-op": newdflags ~= ""; break;
+				//case "-profile": newdflags ~= "-pg"; break;
+				case "-property": newdflags ~= "-fproperty"; break;
+				//case "-quiet": newdflags ~= ""; break;
+				case "-release": newdflags ~= "-frelease"; break;
+				case "-shared": newdflags ~= "-shared"; break;
+				case "-unittest": newdflags ~= "-funittest"; break;
+				case "-v": newdflags ~= "-fd-verbose"; break;
+				//case "-version=[level/ident]": newdflags ~= ""; break;
+				case "-vtls": newdflags ~= "-fd-vtls"; break;
+				case "-w": newdflags ~= "-Werror"; break;
+				case "-wi": newdflags ~= "-Wall"; break;
+				//case "-X": newdflags ~= ""; break;
+				//case "-Xf[file]": newdflags ~= ""; break;
+			}
+		}
+		settings.dflags = newdflags;
+	
+		if( !(fields & BuildSetting.libs) ){
+			try {
+				logDebug("Trying to use pkg-config to resolve library flags for %s.", settings.libs);
+				auto libflags = execute("pkg-config", "--libs" ~ settings.libs.map!(l => "lib"~l)().array());
+				enforce(libflags.status == 0, "pkg-config exited with error code "~to!string(libflags.status));
+				settings.addLFlags(libflags.output.split());
+			} catch( Exception e ){
+				logDebug("pkg-config failed: %s", e.msg);
+				logDebug("Falling back to direct -lxyz flags.");
+				settings.addLFlags(settings.libs.map!(l => "-l"~l)().array());
+			}
+			settings.libs = null;
+		}
+
+		if( !(fields & BuildSetting.versions) ){
+			settings.addDFlags(settings.versions.map!(s => "-fversion="~s)().array());
+			settings.versions = null;
+		}
+
+		if( !(fields & BuildSetting.importPaths) ){
+			settings.addDFlags(settings.importPaths.map!(s => "-I"~s)().array());
+			settings.importPaths = null;
+		}
+
+		if( !(fields & BuildSetting.stringImportPaths) ){
+			settings.addDFlags(settings.stringImportPaths.map!(s => "-J"~s)().array());
+			settings.stringImportPaths = null;
+		}
+
+		if( !(fields & BuildSetting.files) ){
+			settings.addDFlags(settings.files);
+			settings.files = null;
+		}
+
+		if( !(fields & BuildSetting.lflags) ){
+			foreach( f; settings.lflags )
+				settings.addDFlags(["-Xlinker", f]);
+			settings.lflags = null;
+		}
+
+		assert(fields & BuildSetting.dflags);
+		assert(fields & BuildSetting.copyFiles);
+	}
+}