--- a/src/main/java/com/google/devtools/build/lib/bazel/rules/BazelRuleClassProvider.java
+++ b/src/main/java/com/google/devtools/build/lib/bazel/rules/BazelRuleClassProvider.java
@@ -181,6 +181,13 @@ public class BazelRuleClassProvider {
           env.put("PATH", null);
         }
 
+        Map<String, String> spackEnv = System.getenv();
+        for (String envName : spackEnv.keySet()) {
+          if (envName.startsWith("SPACK_")) {
+            env.put(envName, spackEnv.get(envName));
+          }
+        }
+
         // Shell environment variables specified via options take precedence over the
         // ones inherited from the fragments. In the long run, these fragments will
         // be replaced by appropriate default rc files anyway.