diff --git a/releasenotes/notes/csp-layout-extra-b62a5e53f136534a.yaml b/releasenotes/notes/csp-layout-extra-b62a5e53f136534a.yaml
new file mode 100644
index 000000000000..a0863920b33e
--- /dev/null
+++ b/releasenotes/notes/csp-layout-extra-b62a5e53f136534a.yaml
@@ -0,0 +1,11 @@
+---
+upgrade:
+  - |
+    A new extra ``csp-layout-pass`` has been added to the install target for
+    ``pip install qiskit-terra``, and is also included in the ``all`` extra.
+    This has no effect in Qiskit Terra 0.20, but starting from Qiskit Terra 0.21,
+    the dependencies needed only for the :class:`.CSPLayout` transpiler pass will
+    be downgraded from requirements to optionals, and installed by this extra.
+    You can prepare a package that depends on this pass by setting its
+    requirements (or ``pip install`` command) to target
+    ``qiskit-terra[csp-layout-pass]``.
diff --git a/setup.py b/setup.py
index ff6195e84783..d346360119b9 100755
--- a/setup.py
+++ b/setup.py
@@ -33,6 +33,9 @@
     )
 
 
+csplayout_requirements = [
+    "python-constraint>=1.4",
+]
 visualization_extras = [
     "matplotlib>=3.3",
     "ipywidgets>=7.3.0",
@@ -82,10 +85,11 @@
         "visualization": visualization_extras,
         "bip-mapper": bip_requirements,
         "crosstalk-pass": z3_requirements,
+        "csp-layout-pass": csplayout_requirements,
         # Note: 'all' does not include 'bip-mapper' because cplex is too fiddly and too little
         # supported on various Python versions and OSes compared to Terra.  You have to ask for it
         # explicitly.
-        "all": visualization_extras + z3_requirements,
+        "all": visualization_extras + z3_requirements + csplayout_requirements,
     },
     project_urls={
         "Bug Tracker": "https://github.com/Qiskit/qiskit-terra/issues",