diff --git a/app/Engine/Engine.php b/app/Engine/Engine.php
index 2049276..3627843 100644
--- a/app/Engine/Engine.php
+++ b/app/Engine/Engine.php
@@ -55,7 +55,7 @@ class Engine
 
 		$documents = [];
 
-		// First, figure out which files to process and load all files.
+		// Figure out which files to process and load all files.
 		$files = [basename($input_file)];
 
 		for ($i = 0; $i < sizeof($files); $i++)
@@ -79,72 +79,21 @@ class Engine
 			}
 		}
 
-		// Go through and load all the variables and parameters
-		$variables = [];
-		$parameters = [];
-		for ($i = 0; $i < sizeof($files); $i++)
-		{
-			$file_variables = [];
-			try
-			{
-				$file_variables = $documents[$files[$i]]->getMeta('variables');
-			}
-			catch (\Exception $ex)
-			{
-			}
-
-			foreach ($file_variables as $k => $v)
-			{
-				$variables[$k] = $v;
-			}
-
-			$file_parameters = [];
-			try
-			{
-				$file_parameters = $documents[$files[$i]]->getMeta('parameters');
-			}
-			catch (\Exception $ex)
-			{
-			}
-
-			foreach ($file_parameters as $k => $v)
-			{
-				$parameters[$k] = $v;
-			}
-		}
-
-		foreach ($variables as $k => $v)
-		{
-			if (!$options->hasVariable($k))
-			{
-				$options->setVariable($k, $v);
-			}
-		}
-
-		foreach ($parameters as $k => $v)
-		{
-			if (!$options->hasParameter($k))
-			{
-				$options->setParameter($k, $v);
-			}
-		}
-
 		// Now actually process all the documents
-		for ($i = 0; $i < sizeof($files); $i++)
-		{
-			$this->compileDocument($documents[$files[$i]]);
-		}
+		$document = $this->compileDocuments($documents, $options);
 
 		// Set metadata in output
-		$document = $this->getOutputDocument();
-
 		$document->addChildUnderPath('Metadata', new \App\Dom\NodeValue(null, 'Stack', implode(', ', $files)));
+
+		// Remove cfnpp block, that doesn't go to CloudFormation
 		$cfnpp = $document->getChildByName('cfnpp');
 		if (isset($cfnpp))
 		{
 			$cfnpp->remove();
 		}
 
+		// Serialize and return
+		// TODO: We'll want to return parameters/etc later.
 		return $this->serialize->serialize($document);
 	}
 
@@ -193,7 +142,6 @@ class Engine
 	public function setInputDocument(\App\Dom\Document $document): Engine
 	{
 		$this->document = $document;
-		$this->compile->setDocument($document);
 		return $this;
 	}
 
@@ -213,13 +161,14 @@ class Engine
 	/**
 	 * Compile a new document, mutating current state.
 	 *
-	 * @param  string $document_string
+	 * @param  string   $document_string
+	 * @param  IOptions $options
 	 * @return Engine
 	 */
-	public function compile(string $document_string): Engine
+	public function compile(string $document_string, IOptions $options): Engine
 	{
 		$document = $this->unserialize->unserialize($document_string);
-		$this->compileDocument($document);
+		$this->compileDocument($document, $options);
 		return $this;
 	}
 
@@ -227,11 +176,25 @@ class Engine
 	 * Compile a new document, mutating current state.
 	 *
 	 * @param  \App\Dom\Document $document
+	 * @param  IOptions          $options
+	 * @return Engine
+	 */
+	public function compileDocument(\App\Dom\Document $document, IOptions $options): Engine
+	{
+		$this->document = $this->compile->compile(isset($this->document) ? [$this->document, $document] : [$document], $options);
+		return $this;
+	}
+
+	/**
+	 * Compile a set of documents, mutating current state.
+	 *
+	 * @param  \App\Dom\Document[] $documents
+	 * @param  IOptions            $options
 	 * @return Engine
 	 */
-	public function compileDocument(\App\Dom\Document $document): Engine
+	public function compileDocuments(array $documents, IOptions $options): Engine
 	{
-		$this->compile->compile($document);
+		$this->document = $this->compile->compile(isset($this->document) ? array_merge([$this->document], $documents) : $documents, $options);
 		return $this;
 	}
 
@@ -242,7 +205,7 @@ class Engine
 	 */
 	public function getOutputDocument(): \App\Dom\Document
 	{
-		return $this->compile->getDocument();
+		return $this->document;
 	}
 
 	/**