diff --git a/site/content/docs/04-compile-time.md b/site/content/docs/04-compile-time.md
index f9bfa772fec1..fc2b38ad7985 100644
--- a/site/content/docs/04-compile-time.md
+++ b/site/content/docs/04-compile-time.md
@@ -58,7 +58,8 @@ The following options can be passed to the compiler. None are required:
 | `preserveWhitespace` | boolean | `false`
 | `outputFilename` | string | `null`
 | `cssOutputFilename` | string | `null`
-| `sveltePath` | string | `"svelte"` -->
+| `sveltePath` | string | `"svelte"`
+| `prefix` | string | `"svelte-"` -->
 
 | option | default | description |
 | --- | --- | --- |
@@ -80,7 +81,7 @@ The following options can be passed to the compiler. None are required:
 | `outputFilename` | `null` | A `string` used for your JavaScript sourcemap.
 | `cssOutputFilename` | `null` | A `string` used for your CSS sourcemap.
 | `sveltePath` | `"svelte"` | The location of the `svelte` package. Any imports from `svelte` or `svelte/[module]` will be modified accordingly.
-
+| `prefix` | `"svelte-"` | The prefix that will be used for scoping of css classes. It has to start with a `letter`, `-` or `_` and can be followed by `alphanumerics`, `-` or `_`.
 
 ---
 
diff --git a/src/compiler/compile/Component.ts b/src/compiler/compile/Component.ts
index c83f8153a01e..9466a1e47ff4 100644
--- a/src/compiler/compile/Component.ts
+++ b/src/compiler/compile/Component.ts
@@ -29,6 +29,7 @@ import add_to_set from './utils/add_to_set';
 import check_graph_for_cycles from './utils/check_graph_for_cycles';
 import { print, x, b } from 'code-red';
 import { is_reserved_keyword } from './utils/reserved_keywords';
+import get_prefix from './utils/get_prefix';
 
 interface ComponentOptions {
 	namespace?: string;
@@ -133,7 +134,8 @@ export default class Component {
 			source,
 			ast,
 			compile_options.filename,
-			compile_options.dev
+			compile_options.dev,
+			get_prefix(compile_options.prefix),
 		);
 		this.stylesheet.validate(this);
 
diff --git a/src/compiler/compile/css/Stylesheet.ts b/src/compiler/compile/css/Stylesheet.ts
index 246dab0f1219..94cf6641e4c3 100644
--- a/src/compiler/compile/css/Stylesheet.ts
+++ b/src/compiler/compile/css/Stylesheet.ts
@@ -291,14 +291,14 @@ export default class Stylesheet {
 
 	nodes_with_css_class: Set<CssNode> = new Set();
 
-	constructor(source: string, ast: Ast, filename: string, dev: boolean) {
+	constructor(source: string, ast: Ast, filename: string, dev: boolean, prefix: string) {
 		this.source = source;
 		this.ast = ast;
 		this.filename = filename;
 		this.dev = dev;
 
 		if (ast.css && ast.css.children.length) {
-			this.id = `svelte-${hash(ast.css.content.styles)}`;
+			this.id = `${prefix}-${hash(ast.css.content.styles)}`;
 
 			this.has_styles = true;
 
diff --git a/src/compiler/compile/index.ts b/src/compiler/compile/index.ts
index 12b161aeeb0e..cff688b09c00 100644
--- a/src/compiler/compile/index.ts
+++ b/src/compiler/compile/index.ts
@@ -26,7 +26,8 @@ const valid_options = [
 	'css',
 	'loopGuardTimeout',
 	'preserveComments',
-	'preserveWhitespace'
+	'preserveWhitespace',
+	'prefix',
 ];
 
 function validate_options(options: CompileOptions, warnings: Warning[]) {
diff --git a/src/compiler/compile/utils/get_prefix.ts b/src/compiler/compile/utils/get_prefix.ts
new file mode 100644
index 000000000000..9bed13e30b82
--- /dev/null
+++ b/src/compiler/compile/utils/get_prefix.ts
@@ -0,0 +1,9 @@
+export default function get_prefix(str?: string): string {
+    const standard_prefix = 'svelte';
+    if (!str
+        || typeof str !== 'string') return standard_prefix;
+    str = str.replace(/^[^_\-a-z]+|[^_\-a-z0-9]/gi, '');
+    return str.length
+        ? str
+        : standard_prefix;
+}
\ No newline at end of file
diff --git a/src/compiler/interfaces.ts b/src/compiler/interfaces.ts
index a5e286462ff3..05b7fb667a58 100644
--- a/src/compiler/interfaces.ts
+++ b/src/compiler/interfaces.ts
@@ -123,6 +123,7 @@ export interface CompileOptions {
 	tag?: string;
 	css?: boolean;
 	loopGuardTimeout?: number;
+	prefix?: string;
 
 	preserveComments?: boolean;
 	preserveWhitespace?: boolean;
diff --git a/test/css/index.js b/test/css/index.js
index dc17314597fa..5fd9faae0d9e 100644
--- a/test/css/index.js
+++ b/test/css/index.js
@@ -84,7 +84,13 @@ describe('css', () => {
 				css: read(`${__dirname}/samples/${dir}/expected.css`)
 			};
 
-			const actual_css = dom.css.code.replace(/svelte(-ref)?-[a-z0-9]+/g, (m, $1) => $1 ? m : 'svelte-xyz');
+			const replacement = ((config.compileOptions || {}).prefix)
+				? '-xyz{'
+				: 'svelte-xyz';
+			const regex = ((config.compileOptions || {}).prefix)
+				? /(-ref)?-[a-z0-9]+\{/g
+				: /svelte(-ref)?-[a-z0-9]+/g;
+			const actual_css = dom.css.code.replace(regex, (m, $1) => $1 ? m : replacement);
 			try {
 				assert.equal(actual_css, expected.css);
 			} catch (error) {
diff --git a/test/css/samples/custom-prefix-has-only-disallowed-characters/_config.js b/test/css/samples/custom-prefix-has-only-disallowed-characters/_config.js
new file mode 100644
index 000000000000..90eadd250571
--- /dev/null
+++ b/test/css/samples/custom-prefix-has-only-disallowed-characters/_config.js
@@ -0,0 +1,5 @@
+export default {
+	compileOptions: {
+		prefix: ' $!*'
+	}
+};
\ No newline at end of file
diff --git a/test/css/samples/custom-prefix-has-only-disallowed-characters/expected.css b/test/css/samples/custom-prefix-has-only-disallowed-characters/expected.css
new file mode 100644
index 000000000000..5e31d0bc6b09
--- /dev/null
+++ b/test/css/samples/custom-prefix-has-only-disallowed-characters/expected.css
@@ -0,0 +1 @@
+div.svelte-xyz{color:blue}
\ No newline at end of file
diff --git a/test/css/samples/custom-prefix-has-only-disallowed-characters/input.svelte b/test/css/samples/custom-prefix-has-only-disallowed-characters/input.svelte
new file mode 100644
index 000000000000..242eb44a660e
--- /dev/null
+++ b/test/css/samples/custom-prefix-has-only-disallowed-characters/input.svelte
@@ -0,0 +1,7 @@
+<div></div>
+
+<style>
+	div {
+		color: blue;
+	}
+</style>
\ No newline at end of file
diff --git a/test/css/samples/custom-prefix-has-special-character/_config.js b/test/css/samples/custom-prefix-has-special-character/_config.js
new file mode 100644
index 000000000000..18ab64783944
--- /dev/null
+++ b/test/css/samples/custom-prefix-has-special-character/_config.js
@@ -0,0 +1,5 @@
+export default {
+	compileOptions: {
+		prefix: 'me$'
+	}
+};
\ No newline at end of file
diff --git a/test/css/samples/custom-prefix-has-special-character/expected.css b/test/css/samples/custom-prefix-has-special-character/expected.css
new file mode 100644
index 000000000000..2af15fb79732
--- /dev/null
+++ b/test/css/samples/custom-prefix-has-special-character/expected.css
@@ -0,0 +1 @@
+div.me-xyz{color:blue}
\ No newline at end of file
diff --git a/test/css/samples/custom-prefix-has-special-character/input.svelte b/test/css/samples/custom-prefix-has-special-character/input.svelte
new file mode 100644
index 000000000000..242eb44a660e
--- /dev/null
+++ b/test/css/samples/custom-prefix-has-special-character/input.svelte
@@ -0,0 +1,7 @@
+<div></div>
+
+<style>
+	div {
+		color: blue;
+	}
+</style>
\ No newline at end of file
diff --git a/test/css/samples/custom-prefix-has-whitespace/_config.js b/test/css/samples/custom-prefix-has-whitespace/_config.js
new file mode 100644
index 000000000000..ba04f4a11109
--- /dev/null
+++ b/test/css/samples/custom-prefix-has-whitespace/_config.js
@@ -0,0 +1,5 @@
+export default {
+	compileOptions: {
+		prefix: 'm e'
+	}
+};
\ No newline at end of file
diff --git a/test/css/samples/custom-prefix-has-whitespace/expected.css b/test/css/samples/custom-prefix-has-whitespace/expected.css
new file mode 100644
index 000000000000..2af15fb79732
--- /dev/null
+++ b/test/css/samples/custom-prefix-has-whitespace/expected.css
@@ -0,0 +1 @@
+div.me-xyz{color:blue}
\ No newline at end of file
diff --git a/test/css/samples/custom-prefix-has-whitespace/input.svelte b/test/css/samples/custom-prefix-has-whitespace/input.svelte
new file mode 100644
index 000000000000..242eb44a660e
--- /dev/null
+++ b/test/css/samples/custom-prefix-has-whitespace/input.svelte
@@ -0,0 +1,7 @@
+<div></div>
+
+<style>
+	div {
+		color: blue;
+	}
+</style>
\ No newline at end of file
diff --git a/test/css/samples/custom-prefix-no-string/_config.js b/test/css/samples/custom-prefix-no-string/_config.js
new file mode 100644
index 000000000000..616abeeb1343
--- /dev/null
+++ b/test/css/samples/custom-prefix-no-string/_config.js
@@ -0,0 +1,5 @@
+export default {
+	compileOptions: {
+		prefix: true
+	}
+};
\ No newline at end of file
diff --git a/test/css/samples/custom-prefix-no-string/expected.css b/test/css/samples/custom-prefix-no-string/expected.css
new file mode 100644
index 000000000000..5e31d0bc6b09
--- /dev/null
+++ b/test/css/samples/custom-prefix-no-string/expected.css
@@ -0,0 +1 @@
+div.svelte-xyz{color:blue}
\ No newline at end of file
diff --git a/test/css/samples/custom-prefix-no-string/input.svelte b/test/css/samples/custom-prefix-no-string/input.svelte
new file mode 100644
index 000000000000..242eb44a660e
--- /dev/null
+++ b/test/css/samples/custom-prefix-no-string/input.svelte
@@ -0,0 +1,7 @@
+<div></div>
+
+<style>
+	div {
+		color: blue;
+	}
+</style>
\ No newline at end of file
diff --git a/test/css/samples/custom-prefix-starts-with-number/_config.js b/test/css/samples/custom-prefix-starts-with-number/_config.js
new file mode 100644
index 000000000000..3d6f9735fc3d
--- /dev/null
+++ b/test/css/samples/custom-prefix-starts-with-number/_config.js
@@ -0,0 +1,5 @@
+export default {
+	compileOptions: {
+		prefix: '0me'
+	}
+};
\ No newline at end of file
diff --git a/test/css/samples/custom-prefix-starts-with-number/expected.css b/test/css/samples/custom-prefix-starts-with-number/expected.css
new file mode 100644
index 000000000000..2af15fb79732
--- /dev/null
+++ b/test/css/samples/custom-prefix-starts-with-number/expected.css
@@ -0,0 +1 @@
+div.me-xyz{color:blue}
\ No newline at end of file
diff --git a/test/css/samples/custom-prefix-starts-with-number/input.svelte b/test/css/samples/custom-prefix-starts-with-number/input.svelte
new file mode 100644
index 000000000000..242eb44a660e
--- /dev/null
+++ b/test/css/samples/custom-prefix-starts-with-number/input.svelte
@@ -0,0 +1,7 @@
+<div></div>
+
+<style>
+	div {
+		color: blue;
+	}
+</style>
\ No newline at end of file
diff --git a/test/css/samples/custom-prefix-starts-with-whitespace/_config.js b/test/css/samples/custom-prefix-starts-with-whitespace/_config.js
new file mode 100644
index 000000000000..c0f23c1e5897
--- /dev/null
+++ b/test/css/samples/custom-prefix-starts-with-whitespace/_config.js
@@ -0,0 +1,5 @@
+export default {
+	compileOptions: {
+		prefix: ' me'
+	}
+};
\ No newline at end of file
diff --git a/test/css/samples/custom-prefix-starts-with-whitespace/expected.css b/test/css/samples/custom-prefix-starts-with-whitespace/expected.css
new file mode 100644
index 000000000000..2af15fb79732
--- /dev/null
+++ b/test/css/samples/custom-prefix-starts-with-whitespace/expected.css
@@ -0,0 +1 @@
+div.me-xyz{color:blue}
\ No newline at end of file
diff --git a/test/css/samples/custom-prefix-starts-with-whitespace/input.svelte b/test/css/samples/custom-prefix-starts-with-whitespace/input.svelte
new file mode 100644
index 000000000000..242eb44a660e
--- /dev/null
+++ b/test/css/samples/custom-prefix-starts-with-whitespace/input.svelte
@@ -0,0 +1,7 @@
+<div></div>
+
+<style>
+	div {
+		color: blue;
+	}
+</style>
\ No newline at end of file
diff --git a/test/css/samples/custom-prefix/_config.js b/test/css/samples/custom-prefix/_config.js
new file mode 100644
index 000000000000..95391be75ba0
--- /dev/null
+++ b/test/css/samples/custom-prefix/_config.js
@@ -0,0 +1,5 @@
+export default {
+	compileOptions: {
+		prefix: 'me'
+	}
+};
\ No newline at end of file
diff --git a/test/css/samples/custom-prefix/expected.css b/test/css/samples/custom-prefix/expected.css
new file mode 100644
index 000000000000..2af15fb79732
--- /dev/null
+++ b/test/css/samples/custom-prefix/expected.css
@@ -0,0 +1 @@
+div.me-xyz{color:blue}
\ No newline at end of file
diff --git a/test/css/samples/custom-prefix/input.svelte b/test/css/samples/custom-prefix/input.svelte
new file mode 100644
index 000000000000..242eb44a660e
--- /dev/null
+++ b/test/css/samples/custom-prefix/input.svelte
@@ -0,0 +1,7 @@
+<div></div>
+
+<style>
+	div {
+		color: blue;
+	}
+</style>
\ No newline at end of file