diff --git a/zorg/buildbot/builders/ClangBuilder.py b/zorg/buildbot/builders/ClangBuilder.py
index 001d824a3..2c375d211 100644
--- a/zorg/buildbot/builders/ClangBuilder.py
+++ b/zorg/buildbot/builders/ClangBuilder.py
@@ -278,7 +278,8 @@ def _getClangCMakeBuildFactory(
     f = LLVMBuildFactory(
             depends_on_projects=depends_on_projects,
             llvm_srcdir='llvm',
-            enable_runtimes=enable_runtimes)
+            enable_runtimes=enable_runtimes,
+            clean=clean)
 
     # Checkout the latest code for LNT
     # and the test-suite separately. Le's do this first,
diff --git a/zorg/buildbot/process/buildrequest.py b/zorg/buildbot/process/buildrequest.py
index 594a09d25..ebd6371ef 100644
--- a/zorg/buildbot/process/buildrequest.py
+++ b/zorg/buildbot/process/buildrequest.py
@@ -31,6 +31,14 @@ def collapseRequests(master, builder, req1, req2):
             str(req2['buildsetid'])
         )
 
+    # If the build is going to be a clean build anyway, we can collapse a clean
+    # build and a non-clean build.
+    if getattr(builder.config.factory, "clean", False):
+        if 'clean_obj' in selfBuildsetPoperties:
+            del selfBuildsetPoperties["clean_obj"]
+        if 'clean_obj' in otherBuildsetPoperties:
+            del otherBuildsetPoperties["clean_obj"]
+
     # Check buildsets properties and do not collapse
     # if properties do not match. This includes the check
     # for different schedulers.
diff --git a/zorg/buildbot/process/factory.py b/zorg/buildbot/process/factory.py
index b15bbaa19..a2ac70ca8 100644
--- a/zorg/buildbot/process/factory.py
+++ b/zorg/buildbot/process/factory.py
@@ -40,6 +40,8 @@ def __init__(self, steps=None, depends_on_projects=None, hint=None, **kwargs):
         BuildFactory.__init__(self, steps)
 
         self.hint = hint
+
+        self.clean = kwargs.pop('clean', False)
         
         # Handle the dependencies.
         if depends_on_projects is None: