diff --git a/src/main/java/com/android/tools/r8/utils/InternalOptions.java b/src/main/java/com/android/tools/r8/utils/InternalOptions.java
index cecd8b8..83a2245 100644
--- a/src/main/java/com/android/tools/r8/utils/InternalOptions.java
+++ b/src/main/java/com/android/tools/r8/utils/InternalOptions.java
@@ -1154,7 +1154,10 @@
 
   public static class HorizontalClassMergerOptions {
 
-    public boolean enable = true;
+    // TODO(b/138781768): Set enable to true when this bug is resolved.
+    public boolean enable =
+        !Version.isDevelopmentVersion()
+            || System.getProperty("com.android.tools.r8.disableHorizontalClassMerging") == null;
     public boolean enableConstructorMerging = true;
     public boolean enableJavaLambdaMerging = true;