diff --git a/zorg/buildbot/builders/ClangBuilder.py b/zorg/buildbot/builders/ClangBuilder.py
index a003f3987..fffc14618 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..1f5043d11 100644
--- a/zorg/buildbot/process/buildrequest.py
+++ b/zorg/buildbot/process/buildrequest.py
@@ -22,14 +22,20 @@ def collapseRequests(master, builder, req1, req2):
         ('buildsets', str(req2['buildsetid'])))
 
     # Fetch the buildset properties.
-    selfBuildsetPoperties = yield \
-        master.db.buildsets.getBuildsetProperties(
-            str(req1['buildsetid'])
-        )
-    otherBuildsetPoperties = yield \
-        master.db.buildsets.getBuildsetProperties(
-            str(req2['buildsetid'])
-        )
+    selfBuildsetPoperties = yield master.db.buildsets.getBuildsetProperties(
+        str(req1["buildsetid"])
+    )
+    otherBuildsetPoperties = yield master.db.buildsets.getBuildsetProperties(
+        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"):
+        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
diff --git a/zorg/buildbot/process/factory.py b/zorg/buildbot/process/factory.py
index b15bbaa19..e8af8faa0 100644
--- a/zorg/buildbot/process/factory.py
+++ b/zorg/buildbot/process/factory.py
@@ -35,11 +35,15 @@ class LLVMBuildFactory(BuildFactory):
             & etc.
     """
 
-    def __init__(self, steps=None, depends_on_projects=None, hint=None, **kwargs):
+    def __init__(
+        self, steps=None, depends_on_projects=None, hint=None, clean=False, **kwargs
+    ):
         # Cannot use "super" here as BuildFactory is an old style class.
         BuildFactory.__init__(self, steps)
 
         self.hint = hint
+
+        self.clean = clean
         
         # Handle the dependencies.
         if depends_on_projects is None: