diff --git a/packages/metro/src/DeltaBundler/Serializers/__tests__/__snapshots__/getRamBundleInfo-test.js.snap b/packages/metro/src/DeltaBundler/Serializers/__tests__/__snapshots__/getRamBundleInfo-test.js.snap
index 03fdfc2d87..8b64b26da5 100644
--- a/packages/metro/src/DeltaBundler/Serializers/__tests__/__snapshots__/getRamBundleInfo-test.js.snap
+++ b/packages/metro/src/DeltaBundler/Serializers/__tests__/__snapshots__/getRamBundleInfo-test.js.snap
@@ -74,7 +74,7 @@ Object {
       "type": "js/module",
     },
     Object {
-      "code": "__d(function() {foo2()},\\"/root/foo2.js\\",[],\\"foo2.js\\");",
+      "code": "__d(function() {foo2()},\\"/root/foo2.js\\",null,\\"foo2.js\\");",
       "id": "/root/foo2.js",
       "map": Object {
         "sections": Array [
@@ -142,7 +142,7 @@ Object {
       "type": "js/module",
     },
     Object {
-      "code": "__d(function() {baz()},\\"/root/baz.js\\",[],\\"baz.js\\");",
+      "code": "__d(function() {baz()},\\"/root/baz.js\\",null,\\"baz.js\\");",
       "id": "/root/baz.js",
       "map": Object {
         "sections": Array [
@@ -176,7 +176,7 @@ Object {
       "type": "js/module/asset",
     },
     Object {
-      "code": "__d(function() {bar()},\\"/root/bar.js\\",[],\\"bar.js\\");",
+      "code": "__d(function() {bar()},\\"/root/bar.js\\",null,\\"bar.js\\");",
       "id": "/root/bar.js",
       "map": Object {
         "sections": Array [
@@ -210,7 +210,7 @@ Object {
       "type": "js/module",
     },
     Object {
-      "code": "__d(function() {qux()},\\"/root/qux.js\\",[],\\"qux.js\\");",
+      "code": "__d(function() {qux()},\\"/root/qux.js\\",null,\\"qux.js\\");",
       "id": "/root/qux.js",
       "map": Object {
         "sections": Array [
@@ -419,7 +419,7 @@ Object {
       "type": "js/module",
     },
     Object {
-      "code": "__d(function() {foo2()},\\"/root/foo2.js\\",[],\\"foo2.js\\");",
+      "code": "__d(function() {foo2()},\\"/root/foo2.js\\",null,\\"foo2.js\\");",
       "id": "/root/foo2.js",
       "map": Object {
         "sections": Array [
@@ -481,7 +481,7 @@ Object {
       "type": "js/module",
     },
     Object {
-      "code": "__d(function() {baz()},\\"/root/baz.js\\",[],\\"baz.js\\");",
+      "code": "__d(function() {baz()},\\"/root/baz.js\\",null,\\"baz.js\\");",
       "id": "/root/baz.js",
       "map": Object {
         "sections": Array [
@@ -512,7 +512,7 @@ Object {
       "type": "js/module/asset",
     },
     Object {
-      "code": "__d(function() {bar()},\\"/root/bar.js\\",[],\\"bar.js\\");",
+      "code": "__d(function() {bar()},\\"/root/bar.js\\",null,\\"bar.js\\");",
       "id": "/root/bar.js",
       "map": Object {
         "sections": Array [
@@ -543,7 +543,7 @@ Object {
       "type": "js/module",
     },
     Object {
-      "code": "__d(function() {qux()},\\"/root/qux.js\\",[],\\"qux.js\\");",
+      "code": "__d(function() {qux()},\\"/root/qux.js\\",null,\\"qux.js\\");",
       "id": "/root/qux.js",
       "map": Object {
         "sections": Array [
diff --git a/packages/metro/src/DeltaBundler/Serializers/__tests__/baseJSBundle-test.js b/packages/metro/src/DeltaBundler/Serializers/__tests__/baseJSBundle-test.js
index 4a7d9a7ed4..44362481b1 100644
--- a/packages/metro/src/DeltaBundler/Serializers/__tests__/baseJSBundle-test.js
+++ b/packages/metro/src/DeltaBundler/Serializers/__tests__/baseJSBundle-test.js
@@ -155,7 +155,7 @@ test('should generate a very simple bundle', () => {
         ],
         Array [
           "bar",
-          "__d(function() {/* code for bar */},\\"bar\\",[],\\"bar\\");",
+          "__d(function() {/* code for bar */},\\"bar\\",null,\\"bar\\");",
         ],
       ],
       "post": "require(\\"foo\\");
@@ -215,7 +215,7 @@ Object {
   "modules": Array [
     Array [
       "#.js",
-      "__d(function() {/* code for ascii file with non ascii characters: %30.бундл.Øಚ😁AA */},\\"#.js\\",[],\\"%30.бундл.Øಚ😁AA/src/?/foo=bar/#.js\\");",
+      "__d(function() {/* code for ascii file with non ascii characters: %30.бундл.Øಚ😁AA */},\\"#.js\\",null,\\"%30.бундл.Øಚ😁AA/src/?/foo=bar/#.js\\");",
     ],
   ],
   "post": "//# sourceMappingURL=http://localhost/root/%2530.%D0%B1%D1%83%D0%BD%D0%B4%D0%BB.%C3%98%E0%B2%9A%F0%9F%98%81AA/src/%3F/foo%3Dbar/%23.map
@@ -307,7 +307,7 @@ test('should handle numeric module ids', () => {
       ],
       Array [
         1,
-        "__d(function() {/* code for bar */},1,[],\\"bar\\");",
+        "__d(function() {/* code for bar */},1,null,\\"bar\\");",
       ],
     ]
   `);
@@ -540,7 +540,7 @@ test('does not add polyfills when `modulesOnly` is used', () => {
         ],
         Array [
           "bar",
-          "__d(function() {/* code for bar */},\\"bar\\",[],\\"bar\\");",
+          "__d(function() {/* code for bar */},\\"bar\\",null,\\"bar\\");",
         ],
       ],
       "post": "require(\\"foo\\");
diff --git a/packages/metro/src/DeltaBundler/Serializers/__tests__/hmrJSBundle-test.js b/packages/metro/src/DeltaBundler/Serializers/__tests__/hmrJSBundle-test.js
index 3e34298baa..17f9f52b8f 100644
--- a/packages/metro/src/DeltaBundler/Serializers/__tests__/hmrJSBundle-test.js
+++ b/packages/metro/src/DeltaBundler/Serializers/__tests__/hmrJSBundle-test.js
@@ -137,7 +137,7 @@ Object {
     Object {
       "module": Array [
         0,
-        "__d(function() {/* code for bar */},0,[],\\"bar\\",{});
+        "__d(function() {/* code for bar */},0,null,\\"bar\\",{});
 //# sourceMappingURL=http://localhost/bar.map
 //# sourceURL=http://localhost/bar.bundle
 ",
@@ -172,7 +172,7 @@ Object {
     Object {
       "module": Array [
         2,
-        "__d(function() {/* code for ascii file with non ascii characters: %30.бундл.Øಚ😁AA */},2,[],\\"%30.бундл.Øಚ😁AA/src/?/foo=bar/#.js\\",{});
+        "__d(function() {/* code for ascii file with non ascii characters: %30.бундл.Øಚ😁AA */},2,null,\\"%30.бундл.Øಚ😁AA/src/?/foo=bar/#.js\\",{});
 //# sourceMappingURL=http://localhost/%2530.%D0%B1%D1%83%D0%BD%D0%B4%D0%BB.%C3%98%E0%B2%9A%F0%9F%98%81AA/src/%3F/foo%3Dbar/%23.map
 //# sourceURL=http://localhost/%2530.%D0%B1%D1%83%D0%BD%D0%B4%D0%BB.%C3%98%E0%B2%9A%F0%9F%98%81AA/src/%3F/foo%3Dbar/%23.bundle
 ",
diff --git a/packages/metro/src/DeltaBundler/Serializers/helpers/js.js b/packages/metro/src/DeltaBundler/Serializers/helpers/js.js
index e2a0a5db2d..4e9ae64e60 100644
--- a/packages/metro/src/DeltaBundler/Serializers/helpers/js.js
+++ b/packages/metro/src/DeltaBundler/Serializers/helpers/js.js
@@ -165,16 +165,25 @@ export function getModuleParams(
     options,
   );
 
-  const params = [
-    moduleId,
-    hasPaths
-      ? {
-          // $FlowFixMe[not-an-object] Intentionally spreading an array into an object
-          ...dependencyMapArray,
-          paths,
-        }
-      : dependencyMapArray,
-  ];
+  const params: Array<unknown> = [moduleId];
+
+  // As an optimisation: we only emit an argument for the dependency map if
+  // it is non-empty. This is safe because either `dependencyMapReservedName`
+  // is set and we have enforced there are no string occurences of that name,
+  // or we have used `generateUid` to generate an unbound name for it.
+  if (hasPaths) {
+    params.push({
+      // $FlowFixMe[not-an-object] Intentionally spreading an array into an object
+      ...dependencyMapArray,
+      paths,
+    });
+  } else if (dependencyMapArray.length > 0) {
+    params.push(dependencyMapArray);
+  } else if (options.dev) {
+    // In dev we have one more argument (below), so emit a null to preserve its
+    // position.
+    params.push(null);
+  }
 
   if (options.dev) {
     params.push(getModuleVerboseName(module, options));
diff --git a/packages/metro/src/Server/__tests__/Server-test.js b/packages/metro/src/Server/__tests__/Server-test.js
index b92318109e..838170548f 100644
--- a/packages/metro/src/Server/__tests__/Server-test.js
+++ b/packages/metro/src/Server/__tests__/Server-test.js
@@ -346,7 +346,7 @@ describe('processRequest', () => {
         [
           'function () {require();}',
           '__d(function() {entry();},0,[1],"mybundle.js");',
-          '__d(function() {foo();},1,[],"foo.js");',
+          '__d(function() {foo();},1,null,"foo.js");',
           'require(0);',
           '//# sourceMappingURL=http://localhost:8081/mybundle.map?runModule=true',
           '//# sourceURL=http://localhost:8081/mybundle.bundle//&runModule=true',
@@ -362,7 +362,7 @@ describe('processRequest', () => {
       [
         'function () {require();}',
         '__d(function() {entry();},0,[1],"mybundle.js");',
-        '__d(function() {foo();},1,[],"foo.js");',
+        '__d(function() {foo();},1,null,"foo.js");',
         '//# sourceMappingURL=http://localhost:8081/mybundle.map?runModule=false',
         '//# sourceURL=http://localhost:8081/mybundle.bundle//&runModule=false',
       ].join('\n'),
@@ -472,7 +472,7 @@ describe('processRequest', () => {
     expect(response._getString()).toEqual(
       [
         '__d(function() {entry();},0,[1],"mybundle.js");',
-        '__d(function() {foo();},1,[],"foo.js");',
+        '__d(function() {foo();},1,null,"foo.js");',
         '//# sourceMappingURL=http://localhost:8081/mybundle.map?modulesOnly=true&runModule=false',
         '//# sourceURL=http://localhost:8081/mybundle.bundle//&modulesOnly=true&runModule=false',
       ].join('\n'),
@@ -493,7 +493,7 @@ describe('processRequest', () => {
     expect(response._getString()).toEqual(
       [
         '__d(function() {entry();},0,[1],"mybundle.js");',
-        '__d(function() {foo();},1,[],"foo.js");',
+        '__d(function() {foo();},1,null,"foo.js");',
         '//# sourceMappingURL=https://forwardedhost.com/mybundle.map?modulesOnly=true&runModule=false&platform=vr',
         '//# sourceURL=https://forwardedhost.com/mybundle.bundle//&modulesOnly=true&runModule=false&platform=vr',
       ].join('\n'),
@@ -842,7 +842,7 @@ describe('processRequest', () => {
         [
           'function () {require();}',
           '__d(function() {entry();},0,[1],"mybundle.js");',
-          '__d(function() {foo();},1,[],"foo.js");',
+          '__d(function() {foo();},1,null,"foo.js");',
           'require(0);',
           '//# sourceMappingURL=http://localhost:8081/mybundle.map?runModule=true&TEST_URL_WAS_REWRITTEN=true',
           '//# sourceURL=http://localhost:8081/mybundle.bundle//&runModule=true&TEST_URL_WAS_REWRITTEN=true',
diff --git a/packages/metro/src/__tests__/HmrServer-test.js b/packages/metro/src/__tests__/HmrServer-test.js
index 7d0018a003..a6448084e2 100644
--- a/packages/metro/src/__tests__/HmrServer-test.js
+++ b/packages/metro/src/__tests__/HmrServer-test.js
@@ -388,7 +388,7 @@ describe('HmrServer', () => {
                 id('/root/hi'),
                 '__d(function() { alert("hi"); },' +
                   id('/root/hi') +
-                  ',[],"hi",{});\n' +
+                  ',null,"hi",{});\n' +
                   '//# sourceMappingURL=http://localhost/hi.map?platform=ios&dev=true&minify=false&modulesOnly=true&runModule=false&shallow=true\n' +
                   '//# sourceURL=http://localhost/hi.bundle//&platform=ios&dev=true&minify=false&modulesOnly=true&runModule=false&shallow=true\n',
               ],
@@ -472,7 +472,7 @@ describe('HmrServer', () => {
                 id('/root/hi'),
                 '__d(function() { alert("hi"); },' +
                   id('/root/hi') +
-                  ',[],"hi",{});\n' +
+                  ',null,"hi",{});\n' +
                   '//# sourceMappingURL=http://localhost/hi.map?platform=ios&dev=true&minify=false&modulesOnly=true&runModule=false&shallow=true\n' +
                   '//# sourceURL=http://localhost/hi.bundle//&platform=ios&dev=true&minify=false&modulesOnly=true&runModule=false&shallow=true\n',
               ],
@@ -531,7 +531,7 @@ describe('HmrServer', () => {
                 id('/root/hi'),
                 '__d(function() { alert("hi"); },' +
                   id('/root/hi') +
-                  ',[],"hi",{});\n' +
+                  ',null,"hi",{});\n' +
                   '//# sourceMappingURL=http://localhost/hi.map?platform=ios&dev=true&minify=false&modulesOnly=true&runModule=false&shallow=true\n' +
                   '//# sourceURL=http://localhost/hi.bundle//&platform=ios&dev=true&minify=false&modulesOnly=true&runModule=false&shallow=true\n',
               ],
diff --git a/scripts/__tests__/api-snapshots-sync-test.js b/scripts/__tests__/api-snapshots-sync-test.js
index 84fcc484d3..c32c11905e 100644
--- a/scripts/__tests__/api-snapshots-sync-test.js
+++ b/scripts/__tests__/api-snapshots-sync-test.js
@@ -25,4 +25,4 @@ test('Public API snapshots are in sync (yarn run build-api-snapshots produces no
     expect(error.errors).toEqual([]);
   }
   expect(error).toBeUndefined();
-}, 120000);
+}, 180000);