diff --git a/lib/NormalModule.js b/lib/NormalModule.js
index 0136034fb..25d5b7430 100644
--- a/lib/NormalModule.js
+++ b/lib/NormalModule.js
@@ -56,6 +56,7 @@ const makeSerializable = require("./util/makeSerializable");
  * @returns {string} new source path
  */
 const contextifySourceUrl = (context, source, associatedObjectForCache) => {
+	if (source.startsWith("webpack://")) return source;
 	return `webpack://${contextify(context, source, associatedObjectForCache)}`;
 };
 
@@ -67,11 +68,26 @@ const contextifySourceUrl = (context, source, associatedObjectForCache) => {
  */
 const contextifySourceMap = (context, sourceMap, associatedObjectForCache) => {
 	if (!Array.isArray(sourceMap.sources)) return sourceMap;
+	const sourceRoot = sourceMap.sourceRoot;
+	/** @type {function(string): string} */
+	const mapper = !sourceRoot
+		? source => source
+		: sourceRoot.endsWith("/")
+		? source =>
+				source.startsWith("/")
+					? `${sourceRoot.slice(0, -1)}${source}`
+					: `${sourceRoot}${source}`
+		: source =>
+				source.startsWith("/")
+					? `${sourceRoot}${source}`
+					: `${sourceRoot}/${source}`;
 	const newSources = sourceMap.sources.map(source =>
-		contextifySourceUrl(context, source, associatedObjectForCache)
+		contextifySourceUrl(context, mapper(source), associatedObjectForCache)
 	);
 	return {
 		...sourceMap,
+		file: "x",
+		sourceRoot: undefined,
 		sources: newSources
 	};
 };
diff --git a/test/__snapshots__/StatsTestCases.test.js.snap b/test/__snapshots__/StatsTestCases.test.js.snap
index 9d10419ce..992d8dd0e 100644
--- a/test/__snapshots__/StatsTestCases.test.js.snap
+++ b/test/__snapshots__/StatsTestCases.test.js.snap
@@ -684,52 +684,52 @@ exports[`StatsTestCases should print correct stats for concat-and-sideeffects 1`
 `;
 
 exports[`StatsTestCases should print correct stats for context-independence 1`] = `
-"Hash: 7bc8b93f783425f912017bc8b93f783425f912012178c4311212dff34c272178c4311212dff34c27
+"Hash: 3c59c3d45edbe20ee0af3c59c3d45edbe20ee0af39303b7d3ef1ce28f20139303b7d3ef1ce28f201
 Child
-    Hash: 7bc8b93f783425f91201
+    Hash: 3c59c3d45edbe20ee0af
     Time: Xms
     Built at: 1970-04-20 12:42:42
                                Asset       Size
-         703-97267ca95e3cfbc183d4.js  438 bytes  [emitted] [immutable]
-     703-97267ca95e3cfbc183d4.js.map  343 bytes  [emitted] [dev]
-        main-aeb159b6fc904b34b7a7.js   8.02 KiB  [emitted] [immutable]  [name: main]
-    main-aeb159b6fc904b34b7a7.js.map   7.14 KiB  [emitted] [dev]        [name: (main)]
-    Entrypoint main = main-aeb159b6fc904b34b7a7.js (main-aeb159b6fc904b34b7a7.js.map)
+         703-35b05b4f9ece3e5b7253.js  438 bytes  [emitted] [immutable]
+     703-35b05b4f9ece3e5b7253.js.map  343 bytes  [emitted] [dev]
+        main-322147d992bb0a885b10.js   8.02 KiB  [emitted] [immutable]  [name: main]
+    main-322147d992bb0a885b10.js.map   7.14 KiB  [emitted] [dev]        [name: (main)]
+    Entrypoint main = main-322147d992bb0a885b10.js (main-322147d992bb0a885b10.js.map)
     ./a/index.js 40 bytes [built]
     ./a/chunk.js + 1 modules 66 bytes [built]
         + 6 hidden modules
 Child
-    Hash: 7bc8b93f783425f91201
+    Hash: 3c59c3d45edbe20ee0af
     Time: Xms
     Built at: 1970-04-20 12:42:42
                                Asset       Size
-         703-97267ca95e3cfbc183d4.js  438 bytes  [emitted] [immutable]
-     703-97267ca95e3cfbc183d4.js.map  343 bytes  [emitted] [dev]
-        main-aeb159b6fc904b34b7a7.js   8.02 KiB  [emitted] [immutable]  [name: main]
-    main-aeb159b6fc904b34b7a7.js.map   7.14 KiB  [emitted] [dev]        [name: (main)]
-    Entrypoint main = main-aeb159b6fc904b34b7a7.js (main-aeb159b6fc904b34b7a7.js.map)
+         703-35b05b4f9ece3e5b7253.js  438 bytes  [emitted] [immutable]
+     703-35b05b4f9ece3e5b7253.js.map  343 bytes  [emitted] [dev]
+        main-322147d992bb0a885b10.js   8.02 KiB  [emitted] [immutable]  [name: main]
+    main-322147d992bb0a885b10.js.map   7.14 KiB  [emitted] [dev]        [name: (main)]
+    Entrypoint main = main-322147d992bb0a885b10.js (main-322147d992bb0a885b10.js.map)
     ./b/index.js 40 bytes [built]
     ./b/chunk.js + 1 modules 66 bytes [built]
         + 6 hidden modules
 Child
-    Hash: 2178c4311212dff34c27
+    Hash: 39303b7d3ef1ce28f201
     Time: Xms
     Built at: 1970-04-20 12:42:42
                            Asset      Size
-     703-60017c0a0b42e422e290.js  1.49 KiB  [emitted] [immutable]
-    main-96b332b4af5b68dc9590.js  8.91 KiB  [emitted] [immutable]  [name: main]
-    Entrypoint main = main-96b332b4af5b68dc9590.js
+     703-d460da0006247c80e6fd.js  1.49 KiB  [emitted] [immutable]
+    main-d716298143ad43b551dc.js  8.91 KiB  [emitted] [immutable]  [name: main]
+    Entrypoint main = main-d716298143ad43b551dc.js
     ./a/index.js 40 bytes [built]
     ./a/chunk.js + 1 modules 66 bytes [built]
         + 6 hidden modules
 Child
-    Hash: 2178c4311212dff34c27
+    Hash: 39303b7d3ef1ce28f201
     Time: Xms
     Built at: 1970-04-20 12:42:42
                            Asset      Size
-     703-60017c0a0b42e422e290.js  1.49 KiB  [emitted] [immutable]
-    main-96b332b4af5b68dc9590.js  8.91 KiB  [emitted] [immutable]  [name: main]
-    Entrypoint main = main-96b332b4af5b68dc9590.js
+     703-d460da0006247c80e6fd.js  1.49 KiB  [emitted] [immutable]
+    main-d716298143ad43b551dc.js  8.91 KiB  [emitted] [immutable]  [name: main]
+    Entrypoint main = main-d716298143ad43b551dc.js
     ./b/index.js 40 bytes [built]
     ./b/chunk.js + 1 modules 66 bytes [built]
         + 6 hidden modules"
diff --git a/test/configCases/source-map/relative-source-maps-by-loader/index.js b/test/configCases/source-map/relative-source-maps-by-loader/index.js
new file mode 100644
index 000000000..ca4da99d1
--- /dev/null
+++ b/test/configCases/source-map/relative-source-maps-by-loader/index.js
@@ -0,0 +1,19 @@
+it("should run", () => {
+	require("./loader-source-root!");
+	require("./loader-source-root-slash!");
+	require("./loader-source-root-source-slash!");
+	require("./loader-source-root-2-slash!");
+	require("./loader-no-source-root!");
+	require("./loader-pre-relative!");
+});
+
+it("should generate the correct SourceMap", function() {
+	var fs = require("fs");
+	var source = JSON.parse(fs.readFileSync(__filename + ".map", "utf-8"));
+	expect(source.sources).toContain("webpack:///./folder/test1.txt");
+	expect(source.sources).toContain("webpack:///./folder/test2.txt");
+	expect(source.sources).toContain("webpack:///./folder/test3.txt");
+	expect(source.sources).toContain("webpack:///./folder/test4.txt");
+	expect(source.sources).toContain("webpack:///./folder/test5.txt");
+	expect(source.sources).toContain("webpack:///./folder/test6.txt");
+});
diff --git a/test/configCases/source-map/relative-source-maps-by-loader/loader-no-source-root.js b/test/configCases/source-map/relative-source-maps-by-loader/loader-no-source-root.js
new file mode 100644
index 000000000..e30048a3e
--- /dev/null
+++ b/test/configCases/source-map/relative-source-maps-by-loader/loader-no-source-root.js
@@ -0,0 +1,10 @@
+const path = require("path");
+module.exports = function() {
+	this.callback(null, "module.exports = 'ok';", {
+		version: 3,
+		file: "/should/be/removed",
+		sources: [path.join(__dirname, "folder", "test5.txt")],
+		sourcesContent: ["Test"],
+		mappings: "AAAA"
+	});
+};
diff --git a/test/configCases/source-map/relative-source-maps-by-loader/loader-pre-relative.js b/test/configCases/source-map/relative-source-maps-by-loader/loader-pre-relative.js
new file mode 100644
index 000000000..6fe9431ce
--- /dev/null
+++ b/test/configCases/source-map/relative-source-maps-by-loader/loader-pre-relative.js
@@ -0,0 +1,9 @@
+module.exports = function() {
+	this.callback(null, "module.exports = 'ok';", {
+		version: 3,
+		file: "/should/be/removed",
+		sources: ["webpack://./folder/test6.txt"],
+		sourcesContent: ["Test"],
+		mappings: "AAAA"
+	});
+};
diff --git a/test/configCases/source-map/relative-source-maps-by-loader/loader-source-root-2-slash.js b/test/configCases/source-map/relative-source-maps-by-loader/loader-source-root-2-slash.js
new file mode 100644
index 000000000..e5c552d40
--- /dev/null
+++ b/test/configCases/source-map/relative-source-maps-by-loader/loader-source-root-2-slash.js
@@ -0,0 +1,11 @@
+const path = require("path");
+module.exports = function() {
+	this.callback(null, "module.exports = 'ok';", {
+		version: 3,
+		file: "/should/be/removed",
+		sourceRoot: path.join(__dirname, "folder") + "/",
+		sources: ["/test4.txt"],
+		sourcesContent: ["Test"],
+		mappings: "AAAA"
+	});
+};
diff --git a/test/configCases/source-map/relative-source-maps-by-loader/loader-source-root-slash.js b/test/configCases/source-map/relative-source-maps-by-loader/loader-source-root-slash.js
new file mode 100644
index 000000000..0641ad6d5
--- /dev/null
+++ b/test/configCases/source-map/relative-source-maps-by-loader/loader-source-root-slash.js
@@ -0,0 +1,11 @@
+const path = require("path");
+module.exports = function() {
+	this.callback(null, "module.exports = 'ok';", {
+		version: 3,
+		file: "/should/be/removed",
+		sourceRoot: path.join(__dirname, "folder") + "/",
+		sources: ["test3.txt"],
+		sourcesContent: ["Test"],
+		mappings: "AAAA"
+	});
+};
diff --git a/test/configCases/source-map/relative-source-maps-by-loader/loader-source-root-source-slash.js b/test/configCases/source-map/relative-source-maps-by-loader/loader-source-root-source-slash.js
new file mode 100644
index 000000000..dbb0e20bb
--- /dev/null
+++ b/test/configCases/source-map/relative-source-maps-by-loader/loader-source-root-source-slash.js
@@ -0,0 +1,11 @@
+const path = require("path");
+module.exports = function() {
+	this.callback(null, "module.exports = 'ok';", {
+		version: 3,
+		file: "/should/be/removed",
+		sourceRoot: path.join(__dirname, "folder"),
+		sources: ["/test2.txt"],
+		sourcesContent: ["Test"],
+		mappings: "AAAA"
+	});
+};
diff --git a/test/configCases/source-map/relative-source-maps-by-loader/loader-source-root.js b/test/configCases/source-map/relative-source-maps-by-loader/loader-source-root.js
new file mode 100644
index 000000000..a46ea3ff5
--- /dev/null
+++ b/test/configCases/source-map/relative-source-maps-by-loader/loader-source-root.js
@@ -0,0 +1,11 @@
+const path = require("path");
+module.exports = function() {
+	this.callback(null, "module.exports = 'ok';", {
+		version: 3,
+		file: "/should/be/removed",
+		sourceRoot: path.join(__dirname, "folder"),
+		sources: ["test1.txt"],
+		sourcesContent: ["Test"],
+		mappings: "AAAA"
+	});
+};
diff --git a/test/configCases/source-map/relative-source-maps-by-loader/webpack.config.js b/test/configCases/source-map/relative-source-maps-by-loader/webpack.config.js
new file mode 100644
index 000000000..628f31af6
--- /dev/null
+++ b/test/configCases/source-map/relative-source-maps-by-loader/webpack.config.js
@@ -0,0 +1,8 @@
+module.exports = {
+	mode: "development",
+	node: {
+		__dirname: false,
+		__filename: false
+	},
+	devtool: "source-map"
+};