diff --git a/compiler/java/com/google/dart/compiler/CommandLineOptions.java b/compiler/java/com/google/dart/compiler/CommandLineOptions.java
index 91cc50c05ae..ea18b66652c 100644
--- a/compiler/java/com/google/dart/compiler/CommandLineOptions.java
+++ b/compiler/java/com/google/dart/compiler/CommandLineOptions.java
@@ -38,6 +38,10 @@ public class CommandLineOptions {
         usage = "do not generate output, only analyze")
     private boolean checkOnly = false;
 
+    @Option(name = "--disable-type-optimizations",
+            usage = "Debugging: disable type optimizations")
+    private boolean disableTypeOptimizations = false;
+
     @Option(name = "-documentation-lib",
         usage = "only generate documentation for the given library")
     private String documentationLibrary = null;
@@ -53,6 +57,10 @@ public class CommandLineOptions {
         usage = "classes to generate stubs for, comma-separated")
     private String generateIsolateStubs = null;
 
+    @Option(name = "--human-readable-output",
+            usage = "Debugging: generates human readable javascript output")
+    private boolean generateHumanReadableOutput = false;
+
     @Option(name = "--ignore-unrecognized-flags", usage = "ignore unrecognized command line flags")
     private boolean ignoreUnrecognizedFlags = false;
 
@@ -180,6 +188,14 @@ public class CommandLineOptions {
       return batch;
     }
 
+    public boolean disableTypeOptimizations() {
+      return disableTypeOptimizations;
+    }
+
+    public boolean generateHumanReadableOutput() {
+      return generateHumanReadableOutput;
+    }
+
     /**
      * Enables optimization of the generated JavaScript.
      */
diff --git a/compiler/java/com/google/dart/compiler/CompilerConfiguration.java b/compiler/java/com/google/dart/compiler/CompilerConfiguration.java
index 7d28f2b4ded..bdc957adede 100644
--- a/compiler/java/com/google/dart/compiler/CompilerConfiguration.java
+++ b/compiler/java/com/google/dart/compiler/CompilerConfiguration.java
@@ -4,6 +4,7 @@
 
 package com.google.dart.compiler;
 
+import com.google.dart.compiler.CommandLineOptions.CompilerOptions;
 import com.google.dart.compiler.metrics.CompilerMetrics;
 
 import java.io.File;
@@ -87,4 +88,10 @@ public interface CompilerConfiguration {
    * Return the system library corresponding to the specified "dart:<libname>" spec.
    */
   LibrarySource getSystemLibraryFor(String importSpec);
+
+  /**
+   * Return {@link CompilerOptions} instance.
+   * @return command line options passed to the compiler.
+   */
+  CompilerOptions getCompilerOptions();
 }
diff --git a/compiler/java/com/google/dart/compiler/DefaultCompilerConfiguration.java b/compiler/java/com/google/dart/compiler/DefaultCompilerConfiguration.java
index 8ff32c113a4..ecb305ad97a 100644
--- a/compiler/java/com/google/dart/compiler/DefaultCompilerConfiguration.java
+++ b/compiler/java/com/google/dart/compiler/DefaultCompilerConfiguration.java
@@ -53,7 +53,7 @@ public class DefaultCompilerConfiguration implements CompilerConfiguration {
       return new DartIsolateStubGenerator(compilerOptions.getIsolateStubClasses(),
                                           compilerOptions.getIsolateStubOutputFile());
     } else if (compilerOptions.shouldOptimize()) {
-      return new ClosureJsBackend();
+      return new ClosureJsBackend(compilerOptions.generateHumanReadableOutput());
     } else {
       return new JavascriptBackend();
     }
@@ -205,4 +205,9 @@ public class DefaultCompilerConfiguration implements CompilerConfiguration {
     }
     return new UrlLibrarySource(systemUri, this.systemLibraryManager);
   }
+
+  @Override
+  public CompilerOptions getCompilerOptions() {
+    return compilerOptions;
+  }
 }
\ No newline at end of file
diff --git a/compiler/java/com/google/dart/compiler/DelegatingCompilerConfiguration.java b/compiler/java/com/google/dart/compiler/DelegatingCompilerConfiguration.java
index df528a90485..0768cc34ea3 100644
--- a/compiler/java/com/google/dart/compiler/DelegatingCompilerConfiguration.java
+++ b/compiler/java/com/google/dart/compiler/DelegatingCompilerConfiguration.java
@@ -4,6 +4,7 @@
 
 package com.google.dart.compiler;
 
+import com.google.dart.compiler.CommandLineOptions.CompilerOptions;
 import com.google.dart.compiler.metrics.CompilerMetrics;
 
 import java.io.File;
@@ -100,4 +101,9 @@ public class DelegatingCompilerConfiguration implements CompilerConfiguration {
   public LibrarySource getSystemLibraryFor(String importSpec) {
     return delegate.getSystemLibraryFor(importSpec);
   }
+
+  @Override
+  public CompilerOptions getCompilerOptions() {
+    return delegate.getCompilerOptions();
+  }
 }
diff --git a/compiler/java/com/google/dart/compiler/backend/js/AbstractJsBackend.java b/compiler/java/com/google/dart/compiler/backend/js/AbstractJsBackend.java
index af213a9dc2e..6a7ad8e21d4 100644
--- a/compiler/java/com/google/dart/compiler/backend/js/AbstractJsBackend.java
+++ b/compiler/java/com/google/dart/compiler/backend/js/AbstractJsBackend.java
@@ -12,6 +12,7 @@ import com.google.common.collect.Maps;
 import com.google.common.collect.Multimap;
 import com.google.common.collect.Multimaps;
 import com.google.common.collect.Multiset;
+import com.google.dart.compiler.CommandLineOptions.CompilerOptions;
 import com.google.dart.compiler.DartCompilerContext;
 import com.google.dart.compiler.DartSource;
 import com.google.dart.compiler.ast.DartClass;
@@ -308,9 +309,13 @@ public abstract class AbstractJsBackend extends AbstractBackend {
         Tracer.canTrace() ? Tracer.start(DartEventType.TRANSLATE_TO_JS, "unit",
             unit.getSourceName()) : null;
 
-    OptimizationStrategy optimizationStrategy = shouldOptimize() ?
-        new BasicOptimizationStrategy(unit, typeProvider) :
-        new NoOptimizationStrategy(unit, typeProvider);
+    CompilerOptions options = context.getCompilerConfiguration().getCompilerOptions();
+    OptimizationStrategy optimizationStrategy;
+    if (shouldOptimize() && !options.disableTypeOptimizations()) {
+      optimizationStrategy = new BasicOptimizationStrategy(unit, typeProvider);
+    } else {
+      optimizationStrategy = new NoOptimizationStrategy(unit, typeProvider);
+    }
 
      try {
       TraceEvent normalizeEvent =
diff --git a/compiler/java/com/google/dart/compiler/backend/js/ClosureJsBackend.java b/compiler/java/com/google/dart/compiler/backend/js/ClosureJsBackend.java
index 241822fda54..35681b6113f 100644
--- a/compiler/java/com/google/dart/compiler/backend/js/ClosureJsBackend.java
+++ b/compiler/java/com/google/dart/compiler/backend/js/ClosureJsBackend.java
@@ -66,7 +66,18 @@ public class ClosureJsBackend extends AbstractJsBackend {
   private long totalJsOutputCharCount;
 
   // Generate "readable" output for debugging
-  private boolean generateHumanReadableOutput = false;
+  private final boolean generateHumanReadableOutput;
+
+  public ClosureJsBackend() {
+    this.generateHumanReadableOutput = false;
+  }
+
+  /**
+   * @param generateHumanReadableOutput - generates human readable javascript output.
+   */
+  public ClosureJsBackend(boolean generateHumanReadableOutput) {
+    this.generateHumanReadableOutput = generateHumanReadableOutput;
+  }
 
   @Override
   public boolean isOutOfDate(DartSource src, DartCompilerContext context) {
diff --git a/compiler/java/com/google/dart/compiler/testing/TestCompilerConfiguration.java b/compiler/java/com/google/dart/compiler/testing/TestCompilerConfiguration.java
index 055b452bd05..63eeee7b2ce 100644
--- a/compiler/java/com/google/dart/compiler/testing/TestCompilerConfiguration.java
+++ b/compiler/java/com/google/dart/compiler/testing/TestCompilerConfiguration.java
@@ -5,6 +5,7 @@
 package com.google.dart.compiler.testing;
 
 import com.google.dart.compiler.Backend;
+import com.google.dart.compiler.CommandLineOptions.CompilerOptions;
 import com.google.dart.compiler.CompilerConfiguration;
 import com.google.dart.compiler.DartCompilationPhase;
 import com.google.dart.compiler.LibrarySource;
@@ -109,4 +110,9 @@ public class TestCompilerConfiguration implements CompilerConfiguration {
     }
     return new UrlLibrarySource(systemUri, this.systemLibraryManager);
   }
+
+  @Override
+  public CompilerOptions getCompilerOptions() {
+    throw new AssertionError();
+  }
 }