diff --git a/systems/llnl-elcapitan/system.py b/systems/llnl-elcapitan/system.py
index 81612a602..335e39390 100644
--- a/systems/llnl-elcapitan/system.py
+++ b/systems/llnl-elcapitan/system.py
@@ -105,8 +105,30 @@ def external_pkg_configs(self):
         elif self.spec.satisfies("compiler=gcc"):
             selections.append(externals / "libsci" / "00-gcc-packages.yaml")
 
+        cmp_preference_path = self.next_adhoc_cfg()
+        with open(cmp_preference_path, "w") as f:
+            f.write(self.compiler_weighting_cfg())
+        selections.append(cmp_preference_path)
+
         return selections
 
+    def compiler_weighting_cfg(self):
+        compiler = self.spec.variants["compiler"][0]
+
+        if compiler == "cce":
+            return """\
+packages:
+  all:
+    require:
+    - one_of: ["%cce", "%gcc"]
+"""
+        elif compiler == "gcc":
+            return """\
+packages: {}
+"""
+        else:
+            raise ValueError(f"Unexpected value for compiler: {compiler}")
+
     def compiler_configs(self):
         compilers = LlnlElcapitan.resource_location / "compilers"