diff --git a/src/main/java/com/google/api/generator/gapic/protoparser/Parser.java b/src/main/java/com/google/api/generator/gapic/protoparser/Parser.java
index a794bf0d49..b46c94cc9d 100644
--- a/src/main/java/com/google/api/generator/gapic/protoparser/Parser.java
+++ b/src/main/java/com/google/api/generator/gapic/protoparser/Parser.java
@@ -65,6 +65,10 @@ public class Parser {
   private static final String COLON = ":";
   private static final String DEFAULT_PORT = "443";
   private static final String DOT = ".";
+
+  private static final Set<String> DUPE_SERVICE_CODEGEN_BLOCKLIST =
+      new HashSet<>(Arrays.asList("google.longrunning", "google.iam.v1"));
+
   // Allow other parsers to access this.
   protected static final SourceCodeInfoParser SOURCE_CODE_INFO_PARSER = new SourceCodeInfoParser();
 
@@ -131,6 +135,26 @@ public static List<Service> parseServices(
               outputArgResourceNames));
     }
 
+    // Prevent codegen for IAM or LRO if there are other services present, since that is an
+    // indicator that we are not generating a GAPIC client for IAM or LRO.
+    Set<String> serviceProtoPackages =
+        services.stream().map(s -> s.protoPakkage()).collect(Collectors.toSet());
+    boolean servicesContainBlocklistedApi = false;
+    for (String blocklistedPackage : DUPE_SERVICE_CODEGEN_BLOCKLIST) {
+      // It's very unlikely the blocklisted APIs will contain the other, or any other service.
+      if (serviceProtoPackages.contains(blocklistedPackage) && serviceProtoPackages.size() > 1) {
+        servicesContainBlocklistedApi = true;
+        break;
+      }
+    }
+
+    if (servicesContainBlocklistedApi) {
+      services =
+          services.stream()
+              .filter(s -> !DUPE_SERVICE_CODEGEN_BLOCKLIST.contains(s.protoPakkage()))
+              .collect(Collectors.toList());
+    }
+
     return services;
   }