diff --git a/BUILD.gn b/BUILD.gn
index 92bf988e20..efc2371572 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -703,6 +703,7 @@ all_devtools_files = [
   "front_end/terminal/xterm.js/build/xterm.js",
   "front_end/test_runner/module.json",
   "front_end/test_runner/TestRunner.js",
+  "front_end/text_editor/autocompleteTooltip.css",
   "front_end/text_editor/cmdevtools.css",
   "front_end/text_editor/CodeMirrorTextEditor.js",
   "front_end/text_editor/CodeMirrorUtils.js",
diff --git a/front_end/console/ConsolePrompt.js b/front_end/console/ConsolePrompt.js
index 509c25eb15..41902804e7 100644
--- a/front_end/console/ConsolePrompt.js
+++ b/front_end/console/ConsolePrompt.js
@@ -1,9 +1,7 @@
 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
-/**
- * @unrestricted
- */
+
 Console.ConsolePrompt = class extends UI.Widget {
   constructor() {
     super();
@@ -11,6 +9,7 @@ Console.ConsolePrompt = class extends UI.Widget {
     this._history = new Console.ConsoleHistoryManager();
 
     this._initialText = '';
+    /** @type {?UI.TextEditor} */
     this._editor = null;
     this._isBelowPromptEnabled = Runtime.experiments.isEnabled('consoleBelowPrompt');
     this._eagerPreviewElement = createElementWithClass('div', 'console-eager-preview');
@@ -25,6 +24,8 @@ Console.ConsolePrompt = class extends UI.Widget {
     this._eagerPreviewElement.classList.toggle('hidden', !this._eagerEvalSetting.get());
 
     this.element.tabIndex = 0;
+    /** @type {?Promise} */
+    this._previewRequestForTest = null;
 
     self.runtime.extension(UI.TextEditorFactory).instance().then(gotFactory.bind(this));
 
@@ -39,6 +40,7 @@ Console.ConsolePrompt = class extends UI.Widget {
       this._editor.configureAutocomplete({
         substituteRangeCallback: this._substituteRange.bind(this),
         suggestionsCallback: this._wordsWithQuery.bind(this),
+        tooltipCallback: (lineNumber, columnNumber) => this._tooltipCallback(lineNumber, columnNumber)
       });
       this._editor.widget().element.addEventListener('keydown', this._editorKeyDown.bind(this), true);
       this._editor.widget().show(this.element);
@@ -371,6 +373,35 @@ Console.ConsolePrompt = class extends UI.Widget {
         .then(words => words.concat(historyWords));
   }
 
+  /**
+   * @param {number} lineNumber
+   * @param {number} columnNumber
+   * @return {!Promise<?Element>}
+   */
+  async _tooltipCallback(lineNumber, columnNumber) {
+    const before = this._editor.text(new TextUtils.TextRange(0, 0, lineNumber, columnNumber));
+    const result = await ObjectUI.javaScriptAutocomplete.argumentsHint(before);
+    if (!result)
+      return null;
+    const argumentsElement = createElement('span');
+    for (let i = 0; i < result.args.length; i++) {
+      if (i === result.argumentIndex || (i < result.argumentIndex && result.args[i].startsWith('...'))) {
+        const boldElement = createElement('b');
+        boldElement.textContent = result.args[i];
+        argumentsElement.appendChild(boldElement);
+      } else {
+        argumentsElement.createTextChild(result.args[i]);
+      }
+      if (i < result.args.length - 1)
+        argumentsElement.createTextChild(', ');
+    }
+    const tooltip = createElementWithClass('span', 'source-code');
+    tooltip.createTextChild('\u0192(');
+    tooltip.appendChild(argumentsElement);
+    tooltip.createTextChild(')');
+    return tooltip;
+  }
+
   _editorSetForTest() {
   }
 };
diff --git a/front_end/formatter/FormatterWorkerPool.js b/front_end/formatter/FormatterWorkerPool.js
index 6890f5073d..95fe35d428 100644
--- a/front_end/formatter/FormatterWorkerPool.js
+++ b/front_end/formatter/FormatterWorkerPool.js
@@ -239,6 +239,23 @@ Formatter.FormatterWorkerPool = class {
     return /** @type {!Promise<?{baseExpression: string, possibleSideEffects:boolean}>} */ (
         this._runTask('findLastExpression', {content}));
   }
+
+  /**
+   * @param {string} content
+   * @return {!Promise<?{baseExpression: string, possibleSideEffects:boolean, argumentIndex: number}>}
+   */
+  findLastFunctionCall(content) {
+    return /** @type {!Promise<?{baseExpression: string, possibleSideEffects:boolean, argumentIndex: number}>} */ (
+        this._runTask('findLastFunctionCall', {content}));
+  }
+
+  /**
+   * @param {string} content
+   * @return {!Promise<!Array<string>>}
+   */
+  argumentsList(content) {
+    return /** @type {!Promise<!Array<string>>} */ (this._runTask('argumentsList', {content}));
+  }
 };
 
 Formatter.FormatterWorkerPool.MaxWorkers = 2;
diff --git a/front_end/formatter_worker/FormatterWorker.js b/front_end/formatter_worker/FormatterWorker.js
index 791c5a8162..d0d00c6adc 100644
--- a/front_end/formatter_worker/FormatterWorker.js
+++ b/front_end/formatter_worker/FormatterWorker.js
@@ -87,6 +87,12 @@ self.onmessage = function(event) {
     case 'findLastExpression':
       postMessage(FormatterWorker.findLastExpression(params.content));
       break;
+    case 'findLastFunctionCall':
+      postMessage(FormatterWorker.findLastFunctionCall(params.content));
+      break;
+    case 'argumentsList':
+      postMessage(FormatterWorker.argumentsList(params.content));
+      break;
     default:
       console.error('Unsupport method name: ' + method);
   }
@@ -320,6 +326,95 @@ FormatterWorker.format = function(mimeType, text, indentString) {
   postMessage(result);
 };
 
+/**
+ * @param {string} content
+ * @return {?{baseExpression: string, possibleSideEffects:boolean, argumentIndex: number}}
+ */
+FormatterWorker.findLastFunctionCall = function(content) {
+  if (content.length > 10000)
+    return null;
+  try {
+    const tokenizer = acorn.tokenizer(content, {ecmaVersion: 9});
+    while (tokenizer.getToken().type !== acorn.tokTypes.eof) {
+    }
+  } catch (e) {
+    return null;
+  }
+
+  const suffix = '000)';
+  const base = FormatterWorker._lastCompleteExpression(content, suffix, new Set(['CallExpression', 'NewExpression']));
+  if (!base)
+    return null;
+  const callee = base.baseNode['callee'];
+  const argumentIndex = base.baseNode['arguments'].length - 1;
+  const baseExpression = base.baseExpression.substring(callee.start, callee.end);
+  const possibleSideEffects = FormatterWorker._nodeHasPossibleSideEffects(callee);
+  return {baseExpression, possibleSideEffects, argumentIndex};
+};
+
+/**
+ * @param {string} content
+ * @return {!Array<string>}
+ */
+FormatterWorker.argumentsList = function(content) {
+  if (content.length > 10000)
+    return [];
+  let parsed = null;
+  try {
+    // Try to parse as a function, anonymous function, or arrow function.
+    parsed = acorn.parse(`(${content})`, {ecmaVersion: 9});
+  } catch (e) {
+  }
+  if (!parsed) {
+    try {
+      // Try to parse as a method.
+      parsed = acorn.parse(`({${content}})`, {ecmaVersion: 9});
+    } catch (e) {
+    }
+  }
+  if (!parsed || !parsed.body || !parsed.body[0] || !parsed.body[0].expression)
+    return [];
+  const expression = parsed.body[0].expression;
+  let params = null;
+  switch (expression.type) {
+    case 'ClassExpression':
+      if (!expression.body.body)
+        break;
+      const constructor = expression.body.body.find(method => method.kind === 'constructor');
+      if (constructor)
+        params = constructor.value.params;
+      break;
+    case 'ObjectExpression':
+      if (!expression.properties[0] || !expression.properties[0].value)
+        break;
+      params = expression.properties[0].value.params;
+      break;
+    case 'FunctionExpression':
+    case 'ArrowFunctionExpression':
+      params = expression.params;
+      break;
+  }
+  if (!params)
+    return [];
+  return params.map(paramName);
+
+  function paramName(param) {
+    switch (param.type) {
+      case 'Identifier':
+        return param.name;
+      case 'AssignmentPattern':
+        return '?' + paramName(param.left);
+      case 'ObjectPattern':
+        return 'obj';
+      case 'ArrayPattern':
+        return 'arr';
+      case 'RestElement':
+        return '...' + paramName(param.argument);
+    }
+    return '?';
+  }
+};
+
 /**
  * @param {string} content
  * @return {?{baseExpression: string, possibleSideEffects:boolean}}
@@ -335,8 +430,6 @@ FormatterWorker.findLastExpression = function(content) {
     return null;
   }
 
-  /** @type {!ESTree.Node} */
-  let ast;
   const suffix = '.DEVTOOLS';
   try {
     acorn.parse(content + suffix, {ecmaVersion: 9});
@@ -345,6 +438,23 @@ FormatterWorker.findLastExpression = function(content) {
     if (parseError.message.startsWith('Unexpected token') && parseError.pos === content.length)
       return null;
   }
+  const base = FormatterWorker._lastCompleteExpression(content, suffix, new Set(['MemberExpression', 'Identifier']));
+  if (!base)
+    return null;
+  const {baseExpression, baseNode} = base;
+  const possibleSideEffects = FormatterWorker._nodeHasPossibleSideEffects(baseNode);
+  return {baseExpression, possibleSideEffects};
+};
+
+/**
+ * @param {string} content
+ * @param {string} suffix
+ * @param {!Set<string>} types
+ * @return {?{baseNode: !ESTree.Node, baseExpression: string}}
+ */
+FormatterWorker._lastCompleteExpression = function(content, suffix, types) {
+  /** @type {!ESTree.Node} */
+  let ast;
   let parsedContent = '';
   for (let i = 0; i < content.length; i++) {
     try {
@@ -357,7 +467,6 @@ FormatterWorker.findLastExpression = function(content) {
   }
   if (!ast)
     return null;
-  const types = new Set(['MemberExpression', 'Identifier']);
   let baseNode = null;
   const walker = new FormatterWorker.ESTreeWalker(node => {
     if (baseNode || node.end < ast.end)
@@ -371,6 +480,14 @@ FormatterWorker.findLastExpression = function(content) {
   let baseExpression = parsedContent.substring(baseNode.start, parsedContent.length - suffix.length);
   if (baseExpression.startsWith('{'))
     baseExpression = `(${baseExpression})`;
+  return {baseNode, baseExpression};
+};
+
+/**
+ * @param {!ESTree.Node} baseNode
+ * @return {boolean}
+ */
+FormatterWorker._nodeHasPossibleSideEffects = function(baseNode) {
   const sideEffectFreeTypes = new Set([
     'MemberExpression', 'Identifier', 'BinaryExpression', 'Literal', 'TemplateLiteral', 'TemplateElement',
     'ObjectExpression', 'ArrayExpression', 'Property', 'ThisExpression'
@@ -383,7 +500,7 @@ FormatterWorker.findLastExpression = function(content) {
       return FormatterWorker.ESTreeWalker.SkipSubtree;
   });
   sideEffectwalker.walk(/** @type {!ESTree.Node} */ (baseNode));
-  return {baseExpression, possibleSideEffects};
+  return possibleSideEffects;
 };
 
 /**
diff --git a/front_end/object_ui/JavaScriptAutocomplete.js b/front_end/object_ui/JavaScriptAutocomplete.js
index 037dc20106..6b8dfd9979 100644
--- a/front_end/object_ui/JavaScriptAutocomplete.js
+++ b/front_end/object_ui/JavaScriptAutocomplete.js
@@ -32,6 +32,43 @@ ObjectUI.JavaScriptAutocomplete = class {
     return mapCompletions.concat(expressionCompletions);
   }
 
+  /**
+   * @param {string} fullText
+   * @return {!Promise<?{args: !Array<string>, argumentIndex: number}>}
+   */
+  async argumentsHint(fullText) {
+    const functionCall = await Formatter.formatterWorkerPool().findLastFunctionCall(fullText);
+    if (!functionCall)
+      return null;
+    const executionContext = UI.context.flavor(SDK.ExecutionContext);
+    if (!executionContext)
+      return null;
+    const result = await executionContext.evaluate(
+        {
+          expression: functionCall.baseExpression,
+          objectGroup: 'argumentsHint',
+          includeCommandLineAPI: true,
+          silent: true,
+          returnByValue: false,
+          generatePreview: false,
+          throwOnSideEffect: functionCall.possibleSideEffects,
+          timeout: functionCall.possibleSideEffects ? 500 : undefined
+        },
+        /* userGesture */ false, /* awaitPromise */ false);
+    if (!result || result.exceptionDetails || !result.object || result.object.type !== 'function')
+      return null;
+    executionContext.runtimeModel.releaseObjectGroup('argumentsHint');
+
+    const description = result.object.description;
+    if (description.endsWith('{ [native code] }'))
+      return null;  // TODO(einbinder) support native function argument hints
+    const args = await Formatter.formatterWorkerPool().argumentsList(description);
+
+    if (!args.length)
+      return null;
+    return {args, argumentIndex: functionCall.argumentIndex};
+  }
+
   /**
    * @param {string} text
    * @param {string} query
diff --git a/front_end/text_editor/TextEditorAutocompleteController.js b/front_end/text_editor/TextEditorAutocompleteController.js
index 93d4e26613..7a210d9391 100644
--- a/front_end/text_editor/TextEditorAutocompleteController.js
+++ b/front_end/text_editor/TextEditorAutocompleteController.js
@@ -22,7 +22,10 @@ TextEditor.TextEditorAutocompleteController = class {
     this._changes = this._changes.bind(this);
     this._blur = this._blur.bind(this);
     this._beforeChange = this._beforeChange.bind(this);
-    this._mouseDown = this.clearAutocomplete.bind(this);
+    this._mouseDown = () => {
+      this.clearAutocomplete();
+      this._tooltipGlassPane.hide();
+    };
     this._codeMirror.on('changes', this._changes);
     this._lastHintText = '';
     /** @type {?UI.SuggestBox} */
@@ -30,6 +33,14 @@ TextEditor.TextEditorAutocompleteController = class {
     /** @type {?string} */
     this._currentSuggestion = null;
     this._hintElement = createElementWithClass('span', 'auto-complete-text');
+
+    this._tooltipGlassPane = new UI.GlassPane();
+    this._tooltipGlassPane.setSizeBehavior(UI.GlassPane.SizeBehavior.MeasureContent);
+    this._tooltipGlassPane.setOutsideClickCallback(this._tooltipGlassPane.hide.bind(this._tooltipGlassPane));
+    this._tooltipElement = createElementWithClass('div', 'autocomplete-tooltip');
+    const shadowRoot =
+        UI.createShadowRootWithCoreStyles(this._tooltipGlassPane.contentElement, 'text_editor/autocompleteTooltip.css');
+    shadowRoot.appendChild(this._tooltipElement);
   }
 
   _initializeIfNeeded() {
@@ -220,14 +231,14 @@ TextEditor.TextEditorAutocompleteController = class {
   autocomplete(force) {
     this._initializeIfNeeded();
     if (this._codeMirror.somethingSelected()) {
-      this.clearAutocomplete();
+      this._hideSuggestBox();
       return;
     }
 
     const cursor = this._codeMirror.getCursor('head');
     const substituteRange = this._substituteRange(cursor.line, cursor.ch);
     if (!substituteRange || !this._validateSelectionsContexts(substituteRange)) {
-      this.clearAutocomplete();
+      this._hideSuggestBox();
       return;
     }
 
@@ -246,7 +257,7 @@ TextEditor.TextEditorAutocompleteController = class {
     function wordsAcquired(wordsWithQuery) {
       if (!wordsWithQuery.length || (wordsWithQuery.length === 1 && query === wordsWithQuery[0].text) ||
           (!this._suggestBox && hadSuggestBox)) {
-        this.clearAutocomplete();
+        this._hideSuggestBox();
         this._onSuggestionsShownForTest([]);
         return;
       }
@@ -259,6 +270,8 @@ TextEditor.TextEditorAutocompleteController = class {
           queryRange.startColumn !== oldQueryRange.startColumn)
         this._updateAnchorBox();
       this._suggestBox.updateSuggestions(this._anchorBox, wordsWithQuery, true, !this._isCursorAtEndOfLine(), query);
+      if (this._suggestBox.visible)
+        this._tooltipGlassPane.hide();
       this._onSuggestionsShownForTest(wordsWithQuery);
     }
   }
@@ -311,6 +324,11 @@ TextEditor.TextEditorAutocompleteController = class {
   }
 
   clearAutocomplete() {
+    this._tooltipGlassPane.hide();
+    this._hideSuggestBox();
+  }
+
+  _hideSuggestBox() {
     if (!this._suggestBox)
       return;
     this._suggestBox.hide();
@@ -328,6 +346,10 @@ TextEditor.TextEditorAutocompleteController = class {
    * @return {boolean}
    */
   keyDown(event) {
+    if (this._tooltipGlassPane.isShowing() && event.keyCode === UI.KeyboardShortcut.Keys.Esc.code) {
+      this._tooltipGlassPane.hide();
+      return true;
+    }
     if (!this._suggestBox)
       return false;
     switch (event.keyCode) {
@@ -417,6 +439,7 @@ TextEditor.TextEditorAutocompleteController = class {
   }
 
   _onScroll() {
+    this._tooltipGlassPane.hide();
     if (!this._suggestBox)
       return;
     const cursor = this._codeMirror.getCursor();
@@ -431,7 +454,34 @@ TextEditor.TextEditorAutocompleteController = class {
     }
   }
 
+  async _updateTooltip() {
+    const cursor = this._codeMirror.getCursor();
+    const tooltip = this._config.tooltipCallback ? await this._config.tooltipCallback(cursor.line, cursor.ch) : null;
+    const newCursor = this._codeMirror.getCursor();
+
+    if (newCursor.line !== cursor.line && newCursor.ch !== cursor.ch)
+      return;
+    if (this._suggestBox && this._suggestBox.visible)
+      return;
+
+    if (!tooltip) {
+      this._tooltipGlassPane.hide();
+      return;
+    }
+    const metrics = this._textEditor.cursorPositionToCoordinates(cursor.line, cursor.ch);
+    if (!metrics) {
+      this._tooltipGlassPane.hide();
+      return;
+    }
+
+    this._tooltipGlassPane.setContentAnchorBox(new AnchorBox(metrics.x, metrics.y, 0, metrics.height));
+    this._tooltipElement.removeChildren();
+    this._tooltipElement.appendChild(tooltip);
+    this._tooltipGlassPane.show(/** @type {!Document} */ (this._textEditor.element.ownerDocument));
+  }
+
   _onCursorActivity() {
+    this._updateTooltip();
     if (!this._suggestBox)
       return;
     const cursor = this._codeMirror.getCursor();
diff --git a/front_end/text_editor/autocompleteTooltip.css b/front_end/text_editor/autocompleteTooltip.css
new file mode 100644
index 0000000000..f125260837
--- /dev/null
+++ b/front_end/text_editor/autocompleteTooltip.css
@@ -0,0 +1,20 @@
+/*
+ * Copyright (c) 2018 The Chromium Authors. All rights reserved.
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+.autocomplete-tooltip {
+  background-color: #FFFFFF;
+  pointer-events: none;
+  margin-left: -3px;
+  box-shadow: var(--drop-shadow);
+  overflow-x: hidden;
+  height: 20px;
+}
+
+.autocomplete-tooltip > * {
+  padding: 0px 4px;
+  white-space: nowrap;
+  vertical-align: middle;
+  line-height: 20px;
+}
\ No newline at end of file
diff --git a/front_end/text_editor/module.json b/front_end/text_editor/module.json
index 429098b6fd..e1a6b600fc 100644
--- a/front_end/text_editor/module.json
+++ b/front_end/text_editor/module.json
@@ -26,6 +26,7 @@
         "CodeMirrorTextEditor.js"
     ],
     "resources": [
+        "autocompleteTooltip.css",
         "cmdevtools.css"
     ],
     "skip_compilation": [
diff --git a/front_end/ui/TextEditor.js b/front_end/ui/TextEditor.js
index 8bf364db70..d8aeb048bc 100644
--- a/front_end/ui/TextEditor.js
+++ b/front_end/ui/TextEditor.js
@@ -116,6 +116,7 @@ UI.TextEditor.Options;
 /**
  * @typedef {{
  *     substituteRangeCallback: ((function(number, number):?TextUtils.TextRange)|undefined),
+ *     tooltipCallback: ((function(number, number):?Element)|undefined),
  *     suggestionsCallback: ((function(!TextUtils.TextRange, !TextUtils.TextRange, boolean=):?Promise.<!UI.SuggestBox.Suggestions>)|undefined),
  *     isWordChar: ((function(string):boolean)|undefined)
  * }}