diff --git a/src/compiler.cc b/src/compiler.cc
index e9e7dada19..9b25832668 100644
--- a/src/compiler.cc
+++ b/src/compiler.cc
@@ -1690,14 +1690,14 @@ MaybeHandle<SharedFunctionInfo> Compiler::GetSharedFunctionInfoForScript(
         compilation_cache->PutScript(source, isolate->native_context(),
                                      language_mode, inner_result);
         Handle<Script> script(Script::cast(inner_result->script()), isolate);
-        isolate->debug()->OnAfterCompile(script);
         if (isolate->NeedsSourcePositionsForProfiling()) {
           Script::InitLineEnds(script);
         }
-        return inner_result;
+        maybe_result = inner_result;
+      } else {
+        // Deserializer failed. Fall through to compile.
+        compile_timer.set_consuming_code_cache_failed();
       }
-      // Deserializer failed. Fall through to compile.
-      compile_timer.set_consuming_code_cache_failed();
     }
   }
 
@@ -1721,16 +1721,18 @@ MaybeHandle<SharedFunctionInfo> Compiler::GetSharedFunctionInfoForScript(
       DCHECK(result->is_compiled());
       compilation_cache->PutScript(source, isolate->native_context(),
                                    language_mode, result);
-    }
-
-    if (maybe_result.is_null()) {
-      if (natives != EXTENSION_CODE && natives != NATIVES_CODE) {
-        isolate->ReportPendingMessages();
-      }
-    } else {
-      isolate->debug()->OnAfterCompile(script);
+    } else if (maybe_result.is_null() && natives != EXTENSION_CODE &&
+               natives != NATIVES_CODE) {
+      isolate->ReportPendingMessages();
     }
   }
+
+  // On success, report script compilation to debugger.
+  Handle<SharedFunctionInfo> result;
+  if (maybe_result.ToHandle(&result)) {
+    isolate->debug()->OnAfterCompile(handle(Script::cast(result->script())));
+  }
+
   return maybe_result;
 }
 
@@ -1755,43 +1757,67 @@ Compiler::GetSharedFunctionInfoForStreamedScript(
   ParseInfo* parse_info = streaming_data->info.get();
   parse_info->UpdateBackgroundParseStatisticsOnMainThread(isolate);
 
-  Handle<Script> script = NewScript(isolate, source, script_details,
-                                    origin_options, NOT_NATIVES_CODE);
-  parse_info->set_script(script);
-  streaming_data->parser->UpdateStatistics(isolate, script);
-  streaming_data->parser->HandleSourceURLComments(isolate, script);
-
-  if (parse_info->literal() == nullptr) {
-    // Parsing has failed - report error messages.
-    parse_info->pending_error_handler()->ReportErrors(
-        isolate, script, parse_info->ast_value_factory());
-    streaming_data->Release();
-    return MaybeHandle<SharedFunctionInfo>();
+  // Check if compile cache already holds the SFI, if so no need to finalize
+  // the code compiled on the background thread.
+  CompilationCache* compilation_cache = isolate->compilation_cache();
+  MaybeHandle<SharedFunctionInfo> maybe_result =
+      compilation_cache->LookupScript(
+          source, script_details.name_obj, script_details.line_offset,
+          script_details.column_offset, origin_options,
+          isolate->native_context(), parse_info->language_mode());
+  if (!maybe_result.is_null()) {
+    compile_timer.set_hit_isolate_cache();
   }
 
-  // Parsing has succeeded - finalize compilation.
-  MaybeHandle<SharedFunctionInfo> result;
-  if (i::FLAG_background_compile) {
-    // Finalize background compilation.
-    if (streaming_data->outer_function_job) {
-      result = FinalizeTopLevel(parse_info, isolate,
-                                streaming_data->outer_function_job.get(),
-                                &streaming_data->inner_function_jobs);
+  if (maybe_result.is_null()) {
+    // No cache entry found, finalize compilation of the script and add it to
+    // the isolate cache.
+    Handle<Script> script = NewScript(isolate, source, script_details,
+                                      origin_options, NOT_NATIVES_CODE);
+    parse_info->set_script(script);
+    streaming_data->parser->UpdateStatistics(isolate, script);
+    streaming_data->parser->HandleSourceURLComments(isolate, script);
+
+    if (parse_info->literal() == nullptr) {
+      // Parsing has failed - report error messages.
+      parse_info->pending_error_handler()->ReportErrors(
+          isolate, script, parse_info->ast_value_factory());
     } else {
-      // Compilation failed on background thread - throw an exception.
-      FailWithPendingException(isolate, parse_info,
-                               Compiler::ClearExceptionFlag::KEEP_EXCEPTION);
+      // Parsing has succeeded - finalize compilation.
+      if (i::FLAG_background_compile) {
+        // Finalize background compilation.
+        if (streaming_data->outer_function_job) {
+          maybe_result = FinalizeTopLevel(
+              parse_info, isolate, streaming_data->outer_function_job.get(),
+              &streaming_data->inner_function_jobs);
+        } else {
+          // Compilation failed on background thread - throw an exception.
+          FailWithPendingException(
+              isolate, parse_info,
+              Compiler::ClearExceptionFlag::KEEP_EXCEPTION);
+        }
+      } else {
+        // Compilation on main thread.
+        maybe_result = CompileToplevel(parse_info, isolate);
+      }
+    }
+
+    // Add compiled code to the isolate cache.
+    Handle<SharedFunctionInfo> result;
+    if (maybe_result.ToHandle(&result)) {
+      compilation_cache->PutScript(source, isolate->native_context(),
+                                   parse_info->language_mode(), result);
     }
-  } else {
-    // Compilation on main thread.
-    result = CompileToplevel(parse_info, isolate);
   }
 
-  if (!result.is_null()) {
-    isolate->debug()->OnAfterCompile(script);
+  // On success, report script compilation to debugger.
+  Handle<SharedFunctionInfo> result;
+  if (maybe_result.ToHandle(&result)) {
+    isolate->debug()->OnAfterCompile(handle(Script::cast(result->script())));
   }
+
   streaming_data->Release();
-  return result;
+  return maybe_result;
 }
 
 Handle<SharedFunctionInfo> Compiler::GetSharedFunctionInfo(
diff --git a/test/inspector/debugger/step-into-external-async-task.js b/test/inspector/debugger/step-into-external-async-task.js
index 7c7c23816d..b0d55c950d 100644
--- a/test/inspector/debugger/step-into-external-async-task.js
+++ b/test/inspector/debugger/step-into-external-async-task.js
@@ -18,8 +18,11 @@ function store(description) {
 }
 //# sourceURL=utils.js`;
 
-contextGroup1.addScript(utilsScript);
+// TODO(rmcilroy): This has to be in this order since the i::Script object gets
+// reused via the CompilationCache, and we want OnAfterCompile to be called
+// for contextGroup1 last on this script.
 contextGroup2.addScript(utilsScript);
+contextGroup1.addScript(utilsScript);
 
 let frameworkScript = `
 function call(id, f) {