diff --git a/ddoc/.gitignore b/ddoc/.gitignore
new file mode 100644
index 0000000000..646b0fa1e8
--- /dev/null
+++ b/ddoc/.gitignore
@@ -0,0 +1,4 @@
+/libddoc_preprocessor.a
+/ddoc_preprocessor
+/ddoc_preprocessor-test-application
+/ddoc_preprocessor-test-library
diff --git a/ddoc/dub.sdl b/ddoc/dub.sdl
new file mode 100644
index 0000000000..aab1479b34
--- /dev/null
+++ b/ddoc/dub.sdl
@@ -0,0 +1,11 @@
+name "ddoc_preprocessor"
+description "Preprocesses source code before running Ddoc over it"
+dependency "libdparse" version="0.7.2-alpha.4"
+dependency "dmd" path="../../dmd"
+versions "DdocOptions"
+configuration "executable" {
+	versions "IsExecutable"
+	targetType "executable"
+}
+configuration "library" {
+}
diff --git a/ddoc/dub.selections.json b/ddoc/dub.selections.json
new file mode 100644
index 0000000000..e2138fd3b0
--- /dev/null
+++ b/ddoc/dub.selections.json
@@ -0,0 +1,6 @@
+{
+	"fileVersion": 1,
+	"versions": {
+		"libdparse": "0.7.2-alpha.4"
+	}
+}
diff --git a/assert_writeln_magic.d b/ddoc/source/assert_writeln_magic.d
old mode 100755
new mode 100644
similarity index 68%
rename from assert_writeln_magic.d
rename to ddoc/source/assert_writeln_magic.d
index ccfa2b88e7..855c1c8fa8
--- a/assert_writeln_magic.d
+++ b/ddoc/source/assert_writeln_magic.d
@@ -177,7 +177,7 @@ private:
     Out fl;
 }
 
-void parseString(Visitor)(ubyte[] sourceCode, string fileName, Visitor visitor)
+void parseString(Visitor)(ubyte[] sourceCode, Visitor visitor)
 {
     import dparse.lexer;
     import dparse.parser : parseModule;
@@ -188,89 +188,36 @@ void parseString(Visitor)(ubyte[] sourceCode, string fileName, Visitor visitor)
     const(Token)[] tokens = getTokensForParser(sourceCode, config, &cache).array;
 
     RollbackAllocator rba;
-    auto m = parseModule(tokens, fileName, &rba);
+    auto m = parseModule(tokens, "magic.d", &rba);
     visitor.visit(m);
 }
 
-void parseFile(string fileName, string destFile)
+private auto assertWritelnModuleImpl(string fileText)
 {
-    import std.array : uninitializedArray;
-
-    auto inFile = File(fileName);
-    if (inFile.size == 0)
-        warningf("%s is empty", inFile.name);
-
-    ubyte[] sourceCode = uninitializedArray!(ubyte[])(to!size_t(inFile.size));
-    if (sourceCode.length == 0)
-        return;
-
-    inFile.rawRead(sourceCode);
-    auto fl = FileLines(fileName, destFile);
+    import std.string : representation;
+    auto fl = FileLines(fileText);
     auto visitor = new TestVisitor!(typeof(fl))(fl);
-    parseString(sourceCode, fileName, visitor);
+    // libdparse doesn't allow to work on immutable source code
+    parseString(cast(ubyte[]) fileText.representation, visitor);
     delete visitor;
+    return fl;
 }
 
-// Modify a path under oldBase to a new path with the same subpath under newBase.
-// E.g.: `/foo/bar`.rebasePath(`/foo`, `/quux`) == `/quux/bar`
-string rebasePath(string path, string oldBase, string newBase)
+auto assertWritelnModule(string fileText)
 {
-    import std.path : absolutePath, buildPath, relativePath;
-    return buildPath(newBase, path.absolutePath.relativePath(oldBase.absolutePath));
+    return assertWritelnModuleImpl(fileText).buildLines;
 }
-
-version(unittest) { void main(){} } else
-void main(string[] args)
+auto assertWritelnBlock(string fileText)
 {
-    import std.file;
-    import std.getopt;
-    import std.path;
-
-    string inputDir, outputDir;
-    string[] ignoredFiles;
-
-    auto helpInfo = getopt(args, config.required,
-            "inputdir|i", "Folder to start the recursive search for unittest blocks (can be a single file)", &inputDir,
-            "outputdir|o", "Alternative folder to use as output (can be a single file)", &outputDir,
-            "ignore", "List of files to exclude (partial matching is supported)", &ignoredFiles);
-
-    if (helpInfo.helpWanted)
-    {
-        return defaultGetoptPrinter(`assert_writeln_magic
-Tries to lower EqualExpression in AssertExpressions of Unittest blocks to commented writeln calls.
-`, helpInfo.options);
-    }
-
-    inputDir = inputDir.asNormalizedPath.array;
-
-    DirEntry[] files;
-
-    // inputDir as default output directory
-    if (!outputDir.length)
-        outputDir = inputDir;
-
-    if (inputDir.isFile)
-    {
-        files = [DirEntry(inputDir)];
-        inputDir = "";
-    }
-    else
-    {
-        files = dirEntries(inputDir, SpanMode.depth).filter!(
-                a => a.name.endsWith(".d") && !a.name.canFind(".git")).array;
-    }
-
-    foreach (file; files)
+    auto source = "unittest{\n" ~ fileText ~ "}\n";
+    auto fl = assertWritelnModuleImpl(source);
+    auto app = appender!string;
+    foreach (line; fl.lines[1 .. $ - 2])
     {
-        if (!ignoredFiles.any!(x => file.name.canFind(x)))
-        {
-            // single files
-            if (inputDir.length == 0)
-                parseFile(file.name, outputDir);
-            else
-                parseFile(file.name, file.name.rebasePath(inputDir, outputDir));
-        }
+        app ~= line;
+        app ~= "\n";
     }
+    return app.data;
 }
 
 /**
@@ -284,47 +231,26 @@ struct FileLines
 
     string[] lines;
     string destFile;
-    bool overwriteInputFile;
     bool hasWrittenChanges;
 
-    this(string inputFile, string destFile)
-    {
-        stderr.writefln("%s -> %s", inputFile, destFile);
-        this.overwriteInputFile = inputFile == destFile;
-        this.destFile = destFile;
-        lines = File(inputFile).byLineCopy.array;
-
-        destFile.dirName.mkdirRecurse;
-    }
-
-    // dumps all changes
-    ~this()
+    this(string inputText)
     {
-        if (overwriteInputFile)
-        {
-            if (hasWrittenChanges)
-            {
-                auto tmpFile = File(destFile ~ ".tmp", "w");
-                writeLinesToFile(tmpFile);
-                tmpFile.close;
-                tmpFile.name.rename(destFile);
-            }
-        }
-        else
-        {
-            writeLinesToFile(File(destFile, "w"));
-        }
+        lines = inputText.split("\n");
     }
 
     // writes all changes to a random, temporary file
-    void writeLinesToFile(File outFile) {
+    auto buildLines() {
+        auto app = appender!string;
         // dump file
         foreach (line; lines)
-            outFile.writeln(line);
+        {
+            app ~= line;
+            app ~= "\n";
+        }
         // within the docs we automatically inject std.stdio (hence we need to do the same here)
         // writeln needs to be @nogc, @safe, pure and nothrow (we just fake it)
-        outFile.writeln("// \nprivate void writeln(T)(T l) { }");
-        outFile.flush;
+        app ~= "// \nprivate void writeln(T)(T l) { }";
+        return app.data;
     }
 
     string opIndex(size_t i) { return lines[i]; }
@@ -349,7 +275,7 @@ version(unittest)
         import std.string : representation;
         auto mock = FileLinesMock(sourceCode.split("\n"));
         auto visitor = new TestVisitor!(typeof(mock))(mock);
-        parseString(sourceCode.representation.dup, "testmodule", visitor);
+        parseString(sourceCode.representation.dup, visitor);
         delete visitor;
         return mock;
     }
diff --git a/ddoc_preprocessor.d b/ddoc/source/preprocessor.d
old mode 100755
new mode 100644
similarity index 82%
rename from ddoc_preprocessor.d
rename to ddoc/source/preprocessor.d
index 2a425b93bb..8c236e6dee
--- a/ddoc_preprocessor.d
+++ b/ddoc/source/preprocessor.d
@@ -24,12 +24,14 @@ struct Config
 {
     string dmdBinPath = "dmd";
     string outputFile;
-    string cwd = __FILE_FULL_PATH__.dirName;
+    string cwd = __FILE_FULL_PATH__.dirName.dirName.dirName;
 }
 Config config;
 
+version(IsExecutable)
 int main(string[] rootArgs)
 {
+    import assert_writeln_magic;
     import std.getopt;
     auto helpInformation = getopt(
         rootArgs, std.getopt.config.passThrough,
@@ -49,33 +51,71 @@ All unknown options are passed to the compiler.
     assert(pos >= 0, "An input file (.d or .dd) must be provided");
     auto inputFile = args[pos];
     auto text = inputFile.readText;
-    // replace only works with 2.078.1, see: https://github.com/dlang/phobos/pull/6017
-    args = args[0..pos].chain("-".only, args[pos..$].dropOne).array;
+
+    // for now only non-package modules are supported
+    if (!inputFile.endsWith("index.d"))
+        // replace only works with 2.078.1, see: https://github.com/dlang/phobos/pull/6017
+        args = args[0..pos].chain("-".only, args[pos..$].dropOne).array;
 
     // transform and extend the ddoc page
     text = genGrammar(text);
     text = genHeader(text);
     text = genChangelogVersion(inputFile, text);
     text = genSwitches(text);
+    text = fixDdocBugs(inputFile, text);
+
+    // Phobos index.d should have been named index.dd
+    if (inputFile.endsWith(".d") && !inputFile.endsWith("index.d"))
+        text = assertWritelnModule(text);
+
+    string[string] macros;
+    macros["SRC_FILENAME"] = "%s\n".format(inputFile.buildNormalizedPath);
+    return compile(text, args, inputFile, macros);
+}
 
-    // inject custom, "dynamic" macros
-    text ~= "\nSRC_FILENAME=%s\n".format(inputFile.buildNormalizedPath);
-    return compile(text, args);
+auto createTmpDir()
+{
+    import std.uuid : randomUUID;
+    auto dir = tempDir.buildPath("ddoc_preprocessor_" ~ randomUUID.toString.replace("-", ""));
+    mkdir(dir);
+    return dir;
 }
 
-auto compile(R)(R buffer, string[] arguments)
+auto compile(R)(R buffer, string[] arguments, string inputFile, string[string] macros = null)
 {
+    import core.time : usecs;
+    import core.thread : Thread;
     import std.process : pipeProcess, Redirect, wait;
     auto args = [config.dmdBinPath] ~ arguments;
-    foreach (arg; ["-c", "-o-", "-"])
+
+    // Note: ideally we could pass in files directly on stdin.
+    // However, for package.d files, we need to imitate package directory layout to avoid conflicts
+    auto tmpDir = createTmpDir;
+    auto inputTmpFile = tmpDir.buildPath(inputFile);
+    inputTmpFile.dirName.mkdirRecurse;
+    std.file.write(inputTmpFile, buffer);
+    args = args.replace("-", inputTmpFile);
+    scope(exit) tmpDir.rmdirRecurse;
+
+    if (macros !is null)
+    {
+        auto macroString = macros.byPair.map!(a => "%s=%s".format(a[0], a[1])).join("\n");
+        auto macroFile = tmpDir.buildPath("macros.ddoc");
+        std.file.write(macroFile, macroString);
+        args ~= macroFile;
+    }
+
+    foreach (arg; ["-c", "-o-"])
     {
         if (!args.canFind(arg))
             args ~= arg;
     }
     auto pipes = pipeProcess(args, Redirect.stdin);
-    pipes.stdin.write(buffer);
-    pipes.stdin.close;
-    return wait(pipes.pid);
+    import std.process : execute;
+    auto ret = execute(args);
+    if (ret.status != 0)
+        stderr.writeln(ret.output);
+    return ret.status;
 }
 
 // replaces the content of a DDoc macro call
@@ -384,3 +424,18 @@ private void highlightSpecialWords(ref string flag, ref string helpText)
             .to!string;
     }
 }
+
+// Fix ddoc bugs
+string fixDdocBugs(string inputFile, string text)
+{
+
+    // https://github.com/dlang/dlang.org/pull/2069#issuecomment-363154934
+    // can be removed once the Phobos PR is in stable and master
+    // https://github.com/dlang/phobos/pull/6126
+    if (inputFile.endsWith("exception.d"))
+    {
+        text = text.replace(`typeof(new E("", __FILE__, __LINE__)`, `typeof(new E("", string.init, size_t.init)`);
+        text = text.replace(`typeof(new E(__FILE__, __LINE__)`, `typeof(new E(string.init, size_t.init)`);
+    }
+    return text;
+}
\ No newline at end of file
diff --git a/dpl-docs/dub.json b/dpl-docs/dub.json
index 762ed98877..223c4fd718 100644
--- a/dpl-docs/dub.json
+++ b/dpl-docs/dub.json
@@ -1,7 +1,10 @@
 {
 	"name": "dpl-docs",
 	"dependencies": {
-		"ddox": "~>0.16.7"
+		"ddox": "~>0.16.7",
+		"ddoc_preprocessor": {
+		  "path": "../ddoc"
+		}
 	},
 	"versions": ["VibeNoSSL"],
 	"subConfigurations": { "eventcore": "libasync"}
diff --git a/dpl-docs/source/app.d b/dpl-docs/source/app.d
index 66d20e224c..7a5c01b060 100644
--- a/dpl-docs/source/app.d
+++ b/dpl-docs/source/app.d
@@ -1,6 +1,6 @@
 module app;
 
-import ddox.main;
+import ddox_main;
 import std.getopt;
 import std.process;
 import vibe.core.log;
diff --git a/dpl-docs/source/ddox_main.d b/dpl-docs/source/ddox_main.d
new file mode 100644
index 0000000000..02c0f3ac31
--- /dev/null
+++ b/dpl-docs/source/ddox_main.d
@@ -0,0 +1,259 @@
+// Copied from https://github.com/rejectedsoftware/ddox/blob/master/source/ddox/main.d
+module ddox_main;
+
+import ddox.ddoc;
+import ddox.ddox;
+import ddox.entities;
+import ddox.htmlgenerator;
+import ddox.htmlserver;
+import ddox.parsers.dparse;
+import ddox.parsers.jsonparser;
+
+import vibe.core.core;
+import vibe.core.file;
+import vibe.data.json;
+import vibe.inet.url;
+import vibe.http.fileserver;
+import vibe.http.router;
+import vibe.http.server;
+import vibe.stream.operations;
+import std.array;
+import std.exception : enforce;
+import std.file;
+import std.getopt;
+import std.stdio;
+import std.string;
+
+
+int ddoxMain(string[] args)
+{
+	bool help;
+	getopt(args, config.passThrough, "h|help", &help);
+
+	if( args.length < 2 || help ){
+		showUsage(args);
+		return help ? 0 : 1;
+	}
+
+	if( args[1] == "generate-html" && args.length >= 4 )
+		return cmdGenerateHtml(args);
+	if( args[1] == "serve-html" && args.length >= 3 )
+		return cmdServeHtml(args);
+	if( args[1] == "filter" && args.length >= 3 )
+		return cmdFilterDocs(args);
+	if( args[1] == "serve-test" && args.length >= 3 )
+		return cmdServeTest(args);
+	showUsage(args);
+	return 1;
+}
+
+static import ddox.main;
+
+alias cmdGenerateHtml = ddox.main.cmdGenerateHtml;
+alias cmdServeHtml = ddox.main.cmdServeTest;
+alias cmdServeTest = ddox.main.cmdServeTest;
+alias parseDocFile = ddox.main.parseDocFile;
+alias setupGeneratorInput = ddox.main.setupGeneratorInput;
+alias showUsage = ddox.main.showUsage;
+
+int cmdFilterDocs(string[] args)
+{
+	string[] excluded, included;
+	Protection minprot = Protection.Private;
+	bool keeputests = false;
+	bool keepinternals = false;
+	bool unittestexamples = true;
+	bool nounittestexamples = false;
+	bool justdoc = false;
+	getopt(args,
+		//config.passThrough,
+		"ex", &excluded,
+		"in", &included,
+		"min-protection", &minprot,
+		"only-documented", &justdoc,
+		"keep-unittests", &keeputests,
+		"keep-internals", &keepinternals,
+		"unittest-examples", &unittestexamples, // deprecated, kept to not break existing scripts
+		"no-unittest-examples", &nounittestexamples);
+
+	if (keeputests) keepinternals = true;
+	if (nounittestexamples) unittestexamples = false;
+
+	string jsonfile;
+	if( args.length < 3 ){
+		showUsage(args);
+		return 1;
+	}
+
+	Json filterProt(Json json, Json parent, Json last_decl, Json mod)
+	{
+		if (last_decl.type == Json.Type.undefined) last_decl = parent;
+
+		string templateName(Json j){
+			auto n = j["name"].opt!string();
+			auto idx = n.indexOf('(');
+			if( idx >= 0 ) return n[0 .. idx];
+			return n;
+		}
+
+		if( json.type == Json.Type.Object ){
+			auto comment = json["comment"].opt!string;
+			if( justdoc && comment.empty ){
+				if( parent.type != Json.Type.Object || parent["kind"].opt!string() != "template" || templateName(parent) != json["name"].opt!string() )
+					return Json.undefined;
+			}
+
+			Protection prot = Protection.Public;
+			if( auto p = "protection" in json ){
+				switch(p.get!string){
+					default: break;
+					case "private": prot = Protection.Private; break;
+					case "package": prot = Protection.Package; break;
+					case "protected": prot = Protection.Protected; break;
+				}
+			}
+			if( comment.strip == "private" ) prot = Protection.Private;
+			if( prot < minprot ) return Json.undefined;
+
+			auto name = json["name"].opt!string();
+			bool is_internal = name.startsWith("__");
+			bool is_unittest = name.startsWith("__unittest");
+			if (name.startsWith("_staticCtor") || name.startsWith("_staticDtor")) is_internal = true;
+			else if (name.startsWith("_sharedStaticCtor") || name.startsWith("_sharedStaticDtor")) is_internal = true;
+
+			if (unittestexamples && is_unittest && !comment.empty) {
+				assert(last_decl.type == Json.Type.object, "Don't have a last_decl context.");
+				try {
+					string source = extractUnittestSourceCode(json, mod);
+					if (last_decl["comment"].opt!string.empty) {
+						writefln("Warning: Cannot add documented unit test %s to %s, which is not documented.", name, last_decl["name"].opt!string);
+					} else {
+					    import assert_writeln_magic;
+                        auto rewrittenSource = assertWritelnBlock(source);
+                        last_decl["comment"] ~= format("Example:\n%s$(DDOX_UNITTEST_HEADER %s)\n---\n%s\n---\n$(DDOX_UNITTEST_FOOTER %s)\n", comment.strip, name, rewrittenSource, name);
+					}
+				} catch (Exception e) {
+					writefln("Failed to add documented unit test %s:%s as example: %s",
+						mod["file"].get!string(), json["line"].get!long, e.msg);
+					return Json.undefined;
+				}
+			}
+
+			if (!keepinternals && is_internal) return Json.undefined;
+
+			if (!keeputests && is_unittest) return Json.undefined;
+
+			if (auto mem = "members" in json)
+				json["members"] = filterProt(*mem, json, Json.undefined, mod);
+		} else if( json.type == Json.Type.Array ){
+			auto last_child_decl = Json.undefined;
+			Json[] newmem;
+			foreach (m; json) {
+				auto mf = filterProt(m, parent, last_child_decl, mod);
+				if (mf.type == Json.Type.undefined) continue;
+				if (mf.type == Json.Type.object && !mf["name"].opt!string.startsWith("__unittest") && icmp(mf["comment"].opt!string.strip, "ditto") != 0)
+					last_child_decl = mf;
+				newmem ~= mf;
+			}
+			return Json(newmem);
+		}
+		return json;
+	}
+
+	writefln("Reading doc file...");
+	auto text = readText(args[2]);
+	int line = 1;
+	writefln("Parsing JSON...");
+	auto json = parseJson(text, &line);
+
+	writefln("Filtering modules...");
+	Json[] dst;
+	foreach (m; json) {
+		if ("name" !in m) {
+			writefln("No name for module %s - ignoring", m["file"].opt!string);
+			continue;
+		}
+		auto n = m["name"].get!string;
+		bool include = true;
+		foreach (ex; excluded)
+			if (n.startsWith(ex)) {
+				include = false;
+				break;
+			}
+		foreach (inc; included)
+			if (n.startsWith(inc)) {
+				include = true;
+				break;
+			}
+		if (include) {
+			auto doc = filterProt(m, Json.undefined, Json.undefined, m);
+			if (doc.type != Json.Type.undefined)
+				dst ~= doc;
+                }
+	}
+
+	writefln("Writing filtered docs...");
+	auto buf = appender!string();
+	writePrettyJsonString(buf, Json(dst));
+	std.file.write(args[2], buf.data());
+
+	return 0;
+}
+
+// from ddox
+private string extractUnittestSourceCode(Json decl, Json mod)
+{
+	auto filename = mod["file"].get!string();
+	enforce("line" in decl && "endline" in decl, "Missing line/endline fields.");
+	auto from = decl["line"].get!long;
+	auto to = decl["endline"].get!long;
+
+	// read the matching lines out of the file
+	auto app = appender!string();
+	long lc = 1;
+	foreach (str; File(filename).byLine) {
+		if (lc >= from) {
+			app.put(str);
+			app.put('\n');
+		}
+		if (++lc > to) break;
+	}
+	auto ret = app.data;
+
+	// strip the "unittest { .. }" surroundings
+	auto idx = ret.indexOf("unittest");
+	enforce(idx >= 0, format("Missing 'unittest' for unit test at %s:%s.", filename, from));
+	ret = ret[idx .. $];
+
+	idx = ret.indexOf("{");
+	enforce(idx >= 0, format("Missing opening '{' for unit test at %s:%s.", filename, from));
+	ret = ret[idx+1 .. $];
+
+	idx = ret.lastIndexOf("}");
+	enforce(idx >= 0, format("Missing closing '}' for unit test at %s:%s.", filename, from));
+	ret = ret[0 .. idx];
+
+	// unindent lines according to the indentation of the first line
+	app = appender!string();
+	string indent;
+	foreach (i, ln; ret.splitLines) {
+		if (i == 1) {
+			foreach (j; 0 .. ln.length)
+				if (ln[j] != ' ' && ln[j] != '\t') {
+					indent = ln[0 .. j];
+					break;
+				}
+		}
+		if (i > 0 || ln.strip.length > 0) {
+			size_t j = 0;
+			while (j < indent.length && !ln.empty) {
+				if (ln.front != indent[j]) break;
+				ln.popFront();
+				j++;
+			}
+			app.put(ln);
+			app.put('\n');
+		}
+	}
+	return app.data;
+}
diff --git a/posix.mak b/posix.mak
index da7d79be1b..90c0ab1ff5 100644
--- a/posix.mak
+++ b/posix.mak
@@ -126,6 +126,18 @@
 #  in the build folder `.generated`, s.t. Ddoc can be run on the modified sources.
 #
 #  See also: https://dlang.org/blog/2017/03/08/editable-and-runnable-doc-examples-on-dlang-org
+#
+#  Custom DDoc wrapper
+#  -------------------
+#
+#  `ddoc.d` is a wrapper around Ddoc and allows expanding Ddoc macros dynamically
+#  before actually running Ddoc.
+#  Currently this is used for:
+#    - TOC
+#    - dynamic TOC generation
+#    - GRAMMAR overview generation
+#    - CHANGELOG menu generation
+#    - assert -> writeln magic
 PWD=$(shell pwd)
 MAKEFILE=$(firstword $(MAKEFILE_LIST))
 SHELL:=/bin/bash
@@ -171,21 +183,13 @@ $(shell [ ! -d $(DMD_DIR) ] && git clone --depth=1 ${GIT_HOME}/dmd $(DMD_DIR))
 $(shell [ ! -d $(DRUNTIME_DIR) ] && git clone --depth=1 ${GIT_HOME}/druntime $(DRUNTIME_DIR))
 
 ################################################################################
-# Automatically generated directories
-PHOBOS_DIR_GENERATED=$(GENERATED)/phobos-prerelease
-PHOBOS_LATEST_DIR_GENERATED=$(GENERATED)/phobos-latest
-# The assert_writeln_magic tool transforms all source files from Phobos. Hence
-# - a temporary folder with a copy of Phobos needs to be generated
-# - a list of all files in Phobos and the temporary copy is needed to setup proper
-#   Makefile dependencies and rules
+# Automatically clone Phobos
 PHOBOS_FILES := $(shell find $(PHOBOS_DIR) -name '*.d' -o -name '*.mak' -o -name '*.ddoc')
-PHOBOS_FILES_GENERATED := $(subst $(PHOBOS_DIR), $(PHOBOS_DIR_GENERATED), $(PHOBOS_FILES))
 ifndef RELEASE
  # TODO: should be replaced by make targets
  $(shell [ ! -d $(PHOBOS_DIR) ] && git clone --depth=1 ${GIT_HOME}/phobos $(PHOBOS_DIR))
  $(shell [ ! -d $(PHOBOS_LATEST_DIR) ] && git clone -b v${LATEST} --depth=1 ${GIT_HOME}/phobos $(PHOBOS_LATEST_DIR))
  PHOBOS_LATEST_FILES := $(shell find $(PHOBOS_LATEST_DIR) -name '*.d' -o -name '*.mak' -o -name '*.ddoc')
- PHOBOS_LATEST_FILES_GENERATED := $(subst $(PHOBOS_LATEST_DIR), $(PHOBOS_LATEST_DIR_GENERATED), $(PHOBOS_LATEST_FILES))
 endif
 ################################################################################
 
@@ -283,7 +287,7 @@ DDOC_VARS_PRERELEASE_VERBATIM=$(DDOC_VARS_PRERELEASE) \
 # Ddoc binaries
 ################################################################################
 
-DDOC_BIN:=$G/ddoc
+DDOC_BIN:=$G/ddoc_preprocessor
 DDOC_BIN_DMD:=$(DDOC_BIN) --compiler=$(DMD)
 
 ################################################################################
@@ -683,22 +687,26 @@ $W/phobos-prerelease/object.verbatim : $(DMD) $G/changelog/next-version
 ################################################################################
 
 .PHONY: phobos-prerelease
-phobos-prerelease : ${PHOBOS_FILES_GENERATED} druntime-target $(STD_DDOC_PRERELEASE)
-	$(MAKE) --directory=$(PHOBOS_DIR_GENERATED) -f posix.mak html $(DDOC_VARS_PRERELEASE_HTML)
+phobos-prerelease : ${PHOBOS_FILES} druntime-target $(STD_DDOC_PRERELEASE) $(DDOC_BIN) $(DMD) \
+					$G/changelog/next-version
+	$(MAKE) --directory=$(PHOBOS_DIR) -f posix.mak html $(DDOC_VARS_PRERELEASE_HTML) \
+		DMD="$(abspath $(DDOC_BIN)) --compiler=$(abspath $(DMD))"
 
-phobos-release : ${PHOBOS_FILES_GENERATED} druntime-target $(STD_DDOC_RELEASE)
-	$(MAKE) --directory=$(PHOBOS_DIR_GENERATED) -f posix.mak html $(DDOC_VARS_RELEASE_HTML)
+phobos-release : ${PHOBOS_FILES} druntime-target $(STD_DDOC_RELEASE) $(DDOC_BIN) $(DMD)
+	$(MAKE) --directory=$(PHOBOS_DIR) -f posix.mak html $(DDOC_VARS_RELEASE_HTML) \
+		DMD="$(abspath $(DDOC_BIN)) --compiler=$(abspath $(DMD))"
 
-phobos-latest : ${PHOBOS_LATEST_FILES_GENERATED} druntime-latest-target $(STD_DDOC_LATEST)
-	$(MAKE) --directory=$(PHOBOS_LATEST_DIR_GENERATED) -f posix.mak html $(DDOC_VARS_LATEST_HTML)
+phobos-latest : ${PHOBOS_LATEST_FILES} druntime-latest-target $(STD_DDOC_LATEST) $(DDOC_BIN) $(DMD_LATEST)
+	$(MAKE) --directory=$(PHOBOS_LATEST_DIR) -f posix.mak html $(DDOC_VARS_LATEST_HTML) \
+		DMD="$(abspath $(DDOC_BIN)) --compiler=$(abspath $(DMD_LATEST))"
 
-phobos-prerelease-verbatim : ${PHOBOS_FILES_GENERATED} druntime-target \
+phobos-prerelease-verbatim : ${PHOBOS_FILES} druntime-target \
 		$W/phobos-prerelease/index.verbatim
 $W/phobos-prerelease/index.verbatim : verbatim.ddoc \
 		$W/phobos-prerelease/object.verbatim \
-		$W/phobos-prerelease/mars.verbatim $G/changelog/next-version
-	${MAKE} --directory=${PHOBOS_DIR_GENERATED} -f posix.mak html $(DDOC_VARS_PRERELEASE_VERBATIM) \
-	  DOC_OUTPUT_DIR=$W/phobos-prerelease-verbatim
+		$W/phobos-prerelease/mars.verbatim $G/changelog/next-version $(DMD) $(DDOC_BIN)
+	${MAKE} --directory=${PHOBOS_DIR} -f posix.mak html $(DDOC_VARS_PRERELEASE_VERBATIM) \
+	  DOC_OUTPUT_DIR=$W/phobos-prerelease-verbatim DMD="$(abspath $(DDOC_BIN)) --compiler=$(abspath $(DMD))"
 	$(call CHANGE_SUFFIX,html,verbatim,$W/phobos-prerelease-verbatim)
 	mv $W/phobos-prerelease-verbatim/* $(dir $@)
 	rm -r $W/phobos-prerelease-verbatim
@@ -748,7 +756,7 @@ else
 endif
 
 $G/docs-latest.json : ${DMD_LATEST} ${DMD_LATEST_DIR} \
-			${DRUNTIME_LATEST_DIR} ${PHOBOS_LATEST_FILES_GENERATED} | dpl-docs
+			${DRUNTIME_LATEST_DIR} ${PHOBOS_LATEST_FILES} | dpl-docs
 	# remove this after https://github.com/dlang/dmd/pull/7513 has been merged
 	if [ -f $(DMD_LATEST_DIR)/src/*/objc_glue_stubs.d ] ; then \
 	   DMD_EXCLUDE_LATEST_BASH="-e /objc_glue.d/d"; \
@@ -757,17 +765,17 @@ $G/docs-latest.json : ${DMD_LATEST} ${DMD_LATEST_DIR} \
 		sed -e /mscoff/d $${DMD_EXCLUDE_LATEST_BASH} ${DMD_EXCLUDE_LATEST}
 	find ${DRUNTIME_LATEST_DIR}/src -name '*.d' | \
 		sed -e /unittest.d/d -e /gcstub/d >> $G/.latest-files.txt
-	find ${PHOBOS_LATEST_DIR_GENERATED} -name '*.d' | \
+	find ${PHOBOS_LATEST_DIR} -name '*.d' | \
 		sed -e /unittest.d/d | sort >> $G/.latest-files.txt
 	${DMD_LATEST} -J$(DMD_LATEST_DIR)/res -J$(dir $(DMD_LATEST)) -c -o- -version=CoreDdoc \
 		-version=MARS -version=CoreDdoc -version=StdDdoc -Df$G/.latest-dummy.html \
-		-Xf$@ -I${PHOBOS_LATEST_DIR_GENERATED} @$G/.latest-files.txt
+		-Xf$@ -I${PHOBOS_LATEST_DIR} @$G/.latest-files.txt
 	${DPL_DOCS} filter $@ --min-protection=Protected \
 		--only-documented $(MOD_EXCLUDES_LATEST)
 	rm -f $G/.latest-files.txt $G/.latest-dummy.html
 
 $G/docs-prerelease.json : ${DMD} ${DMD_DIR} ${DRUNTIME_DIR} \
-		${PHOBOS_FILES_GENERATED} | dpl-docs
+		${PHOBOS_FILES} | dpl-docs
 	# remove this after https://github.com/dlang/dmd/pull/7513 has been merged
 	if [ -f $(DMD_DIR)/src/*/objc_glue_stubs.d ] ; then \
 	   DMD_EXCLUDE_PRERELEASE="-e /objc_glue.d/d"; \
@@ -776,11 +784,11 @@ $G/docs-prerelease.json : ${DMD} ${DMD_DIR} ${DRUNTIME_DIR} \
 		sed -e /mscoff/d $${DMD_EXCLUDE_PRERELEASE} > $G/.prerelease-files.txt
 	find ${DRUNTIME_DIR}/src -name '*.d' | \
 		sed -e /unittest/d >> $G/.prerelease-files.txt
-	find ${PHOBOS_DIR_GENERATED} -name '*.d' | \
+	find ${PHOBOS_DIR} -name '*.d' | \
 		sed -e /unittest.d/d | sort >> $G/.prerelease-files.txt
 	${DMD} -J$(DMD_DIR)/res -J$(dir $(DMD)) -c -o- -version=MARS -version=CoreDdoc \
 		-version=StdDdoc -Df$G/.prerelease-dummy.html \
-		-Xf$@ -I${PHOBOS_DIR_GENERATED} @$G/.prerelease-files.txt
+		-Xf$@ -I${PHOBOS_DIR} @$G/.prerelease-files.txt
 	${DPL_DOCS} filter $@ --min-protection=Protected \
 		--only-documented $(MOD_EXCLUDES_PRERELEASE)
 	rm -f $G/.prerelease-files.txt $G/.prerelease-dummy.html
@@ -841,42 +849,6 @@ d-release.tag d-tags-release.json : chmgen.d $(STABLE_DMD) $(ALL_FILES) phobos-r
 d-prerelease.tag d-tags-prerelease.json : chmgen.d $(STABLE_DMD) $(ALL_FILES) phobos-prerelease druntime-prerelease chm-nav-prerelease.json
 	$(STABLE_RDMD) chmgen.d --root=$W --target prerelease
 
-################################################################################
-# Assert -> writeln magic
-# -----------------------
-#
-# - This transforms assert(a == b) to writeln(a); // b
-# - It creates a copy of Phobos to apply the transformations
-# - All "d" files are piped through the transformator,
-#   other needed files (e.g. posix.mak) get copied over
-#
-# See also: https://dlang.org/blog/2017/03/08/editable-and-runnable-doc-examples-on-dlang-org
-################################################################################
-
-ASSERT_WRITELN_BIN = $(GENERATED)/assert_writeln_magic
-
-$(ASSERT_WRITELN_BIN): assert_writeln_magic.d $(DUB) $(STABLE_DMD)
-	@mkdir -p $(dir $@)
-	$(DUB) -v build --single --compiler=$(STABLE_DMD) $<
-	@mv ./assert_writeln_magic $@
-
-$(ASSERT_WRITELN_BIN)_test: assert_writeln_magic.d $(DUB) $(STABLE_DMD)
-	@mkdir -p $(dir $@)
-	$(DUB) -v build --single --compiler=$(STABLE_DMD) --build=unittest $<
-	@mv ./assert_writeln_magic $@
-
-$(PHOBOS_FILES_GENERATED): $(PHOBOS_DIR_GENERATED)/%: $(PHOBOS_DIR)/% $(DUB) $(ASSERT_WRITELN_BIN)
-	@mkdir -p $(dir $@)
-	@if [ $(subst .,, $(suffix $@)) = "d" ] && [ "$@" != "$(PHOBOS_DIR_GENERATED)/index.d" ] ; then \
-		$(ASSERT_WRITELN_BIN) -i $< -o $@ ; \
-	else cp $< $@ ; fi
-
-$(PHOBOS_LATEST_FILES_GENERATED): $(PHOBOS_LATEST_DIR_GENERATED)/%: $(PHOBOS_LATEST_DIR)/% $(DUB) $(ASSERT_WRITELN_BIN)
-	@mkdir -p $(dir $@)
-	@if [ $(subst .,, $(suffix $@)) = "d" ] && [ "$@" != "$(PHOBOS_LATEST_DIR_GENERATED)/index.d" ] ; then \
-		$(ASSERT_WRITELN_BIN) -i $< -o $@ ; \
-	else cp $< $@ ; fi
-
 ################################################################################
 # Style tests
 ################################################################################
@@ -886,7 +858,7 @@ test_dspec: dspec_tester.d $(DMD) $(PHOBOS_LIB)
 	$(DMD) -run $< --compiler=$(DMD)
 
 .PHONY:
-test: $(ASSERT_WRITELN_BIN)_test test_dspec test/next_version.sh all | $(STABLE_DMD)
+test: test_dspec test/next_version.sh all | $(STABLE_DMD) $(DUB)
 	@echo "Searching for trailing whitespace"
 	@grep -n '[[:blank:]]$$' $$(find . -type f -name "*.dd" | grep -v .generated) ; test $$? -eq 1
 	@echo "Searching for tabs"
@@ -894,8 +866,8 @@ test: $(ASSERT_WRITELN_BIN)_test test_dspec test/next_version.sh all | $(STABLE_
 	@echo "Checking DDoc's output"
 	$(STABLE_RDMD) -main -unittest check_ddoc.d
 	$(STABLE_RDMD) check_ddoc.d $$(find $W -type f -name "*.html" -not -path "$W/phobos/*")
-	@echo "Executing assert_writeln_magic tests"
-	$<
+	@echo "Executing ddoc_preprocessor tests"
+	$(DUB) test --compiler=${STABLE_DMD} --root ddoc
 	@echo "Executing next_version tests"
 	test/next_version.sh
 
@@ -983,12 +955,12 @@ $G/contributors_list.ddoc:  | $(STABLE_RDMD) $(TOOLS_DIR) $(INSTALLER_DIR)
 # Custom DDoc wrapper
 # ------------------
 #
-# This allows extending Ddoc files dynamically on-the-fly.
-# It is currently only used for the specification pages
+# This allows extending Ddoc files and D source code files dynamically on-the-fly.
 ################################################################################
 
-$(DDOC_BIN): ddoc_preprocessor.d | $(STABLE_DMD) $(DMD)
-	$(STABLE_RDMD) -version=DdocOptions --build-only -g -of$@ -I$(DMD_DIR)/src $<
+$(DDOC_BIN): ddoc/source/preprocessor.d ddoc/source/assert_writeln_magic.d | $(STABLE_DMD)
+	$(STABLE_DMD_BIN_ROOT)/dub build --compiler=$(STABLE_DMD) --root=ddoc && \
+		mv ddoc/ddoc_preprocessor $@
 
 ################################################################################
 # Build and render the DMD man page