diff --git a/res/css/_components.scss b/res/css/_components.scss
index 213d0d714c..40a797dc15 100644
--- a/res/css/_components.scss
+++ b/res/css/_components.scss
@@ -99,6 +99,7 @@
 @import "./views/elements/_ResizeHandle.scss";
 @import "./views/elements/_RichText.scss";
 @import "./views/elements/_RoleButton.scss";
+@import "./views/elements/_RoomAliasField.scss";
 @import "./views/elements/_Spinner.scss";
 @import "./views/elements/_SyntaxHighlight.scss";
 @import "./views/elements/_TextWithTooltip.scss";
diff --git a/res/css/views/elements/_Field.scss b/res/css/views/elements/_Field.scss
index 0e8252e89d..da896f947d 100644
--- a/res/css/views/elements/_Field.scss
+++ b/res/css/views/elements/_Field.scss
@@ -31,6 +31,10 @@ limitations under the License.
     border-right: 1px solid $input-border-color;
 }
 
+.mx_Field_postfix {
+    border-left: 1px solid $input-border-color;
+}
+
 .mx_Field input,
 .mx_Field select,
 .mx_Field textarea {
diff --git a/res/css/views/elements/_RoomAliasField.scss b/res/css/views/elements/_RoomAliasField.scss
new file mode 100644
index 0000000000..0fe53b2766
--- /dev/null
+++ b/res/css/views/elements/_RoomAliasField.scss
@@ -0,0 +1,56 @@
+/*
+Copyright 2019 The Matrix.org Foundation C.I.C.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+.mx_RoomAliasField {
+    // if parent is a flex container, this allows the
+    // width to be as wide as needed, and not 100%
+    flex: 0 1 auto;
+    display: flex;
+    align-items: stretch;
+    min-width: 0;
+    max-width: 100%;
+
+    input {
+        width: 150px;
+        padding-left: 0;
+        padding-right: 0;
+    }
+
+    input::placeholder {
+        color: $greyed-fg-color;
+        font-weight: normal;
+    }
+
+    .mx_Field_prefix, .mx_Field_postfix {
+        color: $greyed-fg-color;
+        border-left: none;
+        border-right: none;
+        font-weight: 600;
+        padding: 9px 10px;
+        flex: 0 0 auto;
+    }
+
+    .mx_Field_postfix {
+        text-overflow: ellipsis;
+        white-space: nowrap;
+        overflow: hidden;
+        // this allows the domain name to show
+        // as long as it doesn't make the input shrink
+        // if it's too big, it shows an ellipsis
+        // 180: 28 for prefix, 152 for input
+        max-width: calc(100% - 180px);
+    }
+}
diff --git a/src/components/views/elements/Field.js b/src/components/views/elements/Field.js
index 08a578b963..0a737d963a 100644
--- a/src/components/views/elements/Field.js
+++ b/src/components/views/elements/Field.js
@@ -41,6 +41,8 @@ export default class Field extends React.PureComponent {
         value: PropTypes.string.isRequired,
         // Optional component to include inside the field before the input.
         prefix: PropTypes.node,
+        // Optional component to include inside the field after the input.
+        postfix: PropTypes.node,
         // The callback called whenever the contents of the field
         // changes.  Returns an object with `valid` boolean field
         // and a `feedback` react component field to provide feedback
@@ -54,6 +56,8 @@ export default class Field extends React.PureComponent {
         // If specified alongside tooltipContent, the class name to apply to the
         // tooltip itself.
         tooltipClassName: PropTypes.string,
+        // If specified, an additional class name to apply to the field container
+        className: PropTypes.string,
         // All other props pass through to the <input>.
     };
 
@@ -143,8 +147,8 @@ export default class Field extends React.PureComponent {
 
     render() {
         const {
-            element, prefix, onValidate, children, tooltipContent, flagInvalid,
-            tooltipClassName, ...inputProps} = this.props;
+            element, prefix, postfix, className, onValidate, children,
+            tooltipContent, flagInvalid, tooltipClassName, ...inputProps} = this.props;
 
         const inputElement = element || "input";
 
@@ -163,9 +167,13 @@ export default class Field extends React.PureComponent {
         if (prefix) {
             prefixContainer = <span className="mx_Field_prefix">{prefix}</span>;
         }
+        let postfixContainer = null;
+        if (postfix) {
+            postfixContainer = <span className="mx_Field_postfix">{postfix}</span>;
+        }
 
         const hasValidationFlag = flagInvalid !== null && flagInvalid !== undefined;
-        const fieldClasses = classNames("mx_Field", `mx_Field_${inputElement}`, {
+        const fieldClasses = classNames("mx_Field", `mx_Field_${inputElement}`, className, {
             // If we have a prefix element, leave the label always at the top left and
             // don't animate it, as it looks a bit clunky and would add complexity to do
             // properly.
@@ -192,6 +200,7 @@ export default class Field extends React.PureComponent {
             {prefixContainer}
             {fieldInput}
             <label htmlFor={this.props.id}>{this.props.label}</label>
+            {postfixContainer}
             {fieldTooltip}
         </div>;
     }
diff --git a/src/components/views/elements/RoomAliasField.js b/src/components/views/elements/RoomAliasField.js
new file mode 100644
index 0000000000..03f4000e59
--- /dev/null
+++ b/src/components/views/elements/RoomAliasField.js
@@ -0,0 +1,125 @@
+/*
+Copyright 2019 New Vector Ltd
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+import { _t } from '../../../languageHandler';
+import React from 'react';
+import PropTypes from 'prop-types';
+import sdk from '../../../index';
+import withValidation from './Validation';
+import MatrixClientPeg from '../../../MatrixClientPeg';
+
+export default class RoomAliasField extends React.PureComponent {
+    static propTypes = {
+        id: PropTypes.string.isRequired,
+        domain: PropTypes.string.isRequired,
+        onChange: PropTypes.func,
+    };
+
+    constructor(props) {
+        super(props);
+        this.state = {isValid: true};
+    }
+
+    _asFullAlias(localpart) {
+        return `#${localpart}:${this.props.domain}`;
+    }
+
+    render() {
+        const Field = sdk.getComponent('views.elements.Field');
+        const poundSign = (<span>#</span>);
+        const aliasPostfix = ":" + this.props.domain;
+        const domain = (<span title={aliasPostfix}>{aliasPostfix}</span>);
+        const maxlength = 255 - this.props.domain.length - 2;   // 2 for # and :
+        return (
+                <Field
+                    label={_t("Room alias")}
+                    className="mx_RoomAliasField"
+                    prefix={poundSign}
+                    postfix={domain}
+                    id={this.props.id}
+                    ref={ref => this._fieldRef = ref}
+                    onValidate={this._onValidate}
+                    placeholder={_t("e.g. my-room")}
+                    onChange={this._onChange}
+                    maxLength={maxlength} />
+        );
+    }
+
+    _onChange = (ev) => {
+        if (this.props.onChange) {
+            this.props.onChange(this._asFullAlias(ev.target.value));
+        }
+    }
+
+    _onValidate = async (fieldState) => {
+        const result = await this._validationRules(fieldState);
+        this.setState({isValid: result.valid});
+        return result;
+    };
+
+    _validationRules = withValidation({
+        rules: [
+            {
+                key: "safeLocalpart",
+                test: async ({ value }) => {
+                    if (!value) {
+                        return true;
+                    }
+                    const fullAlias = this._asFullAlias(value);
+                    // XXX: FIXME https://github.com/matrix-org/matrix-doc/issues/668
+                    return !value.includes("#") && !value.includes(":") && !value.includes(",") &&
+                        encodeURI(fullAlias) === fullAlias;
+                },
+                invalid: () => _t("Some characters not allowed"),
+            }, {
+                key: "required",
+                test: async ({ value, allowEmpty }) => allowEmpty || !!value,
+                invalid: () => _t("Please provide a room alias"),
+            }, {
+                key: "taken",
+                test: async ({value}) => {
+                    if (!value) {
+                        return true;
+                    }
+                    const client = MatrixClientPeg.get();
+                    try {
+                        await client.getRoomIdForAlias(this._asFullAlias(value));
+                        // we got a room id, so the alias is taken
+                        return false;
+                    } catch (err) {
+                        // any server error code will do,
+                        // either it M_NOT_FOUND or the alias is invalid somehow,
+                        // in which case we don't want to show the invalid message
+                        return !!err.errcode;
+                    }
+                },
+                valid: () => _t("This alias is available to use"),
+                invalid: () => _t("This alias is already in use"),
+            },
+        ],
+    });
+
+    get isValid() {
+        return this.state.isValid;
+    }
+
+    validate(options) {
+        return this._fieldRef.validate(options);
+    }
+
+    focus() {
+        this._fieldRef.focus();
+    }
+}