diff --git a/DevTools/HackStudio/Editor.cpp b/DevTools/HackStudio/Editor.cpp
index 275fe3cdf5..2e1a0fa188 100644
--- a/DevTools/HackStudio/Editor.cpp
+++ b/DevTools/HackStudio/Editor.cpp
@@ -25,6 +25,7 @@
  */
 
 #include "Editor.h"
+#include "CppAutoComplete.h"
 #include "EditorWrapper.h"
 #include <AK/ByteBuffer.h>
 #include <AK/LexicalPath.h>
@@ -53,6 +54,8 @@ Editor::Editor()
     m_documentation_tooltip_window->set_rect(0, 0, 500, 400);
     m_documentation_tooltip_window->set_window_type(GUI::WindowType::Tooltip);
     m_documentation_page_view = m_documentation_tooltip_window->set_main_widget<Web::InProcessWebView>();
+
+    m_autocomplete_box = make<AutoCompleteBox>(make_weak_ptr());
 }
 
 Editor::~Editor()
@@ -307,9 +310,49 @@ void Editor::mousedown_event(GUI::MouseEvent& event)
 
 void Editor::keydown_event(GUI::KeyEvent& event)
 {
+    if (m_autocomplete_in_focus) {
+        if (event.key() == Key_Escape) {
+            m_autocomplete_in_focus = false;
+            m_autocomplete_box->close();
+            return;
+        }
+        if (event.key() == Key_Down) {
+            m_autocomplete_box->next_suggestion();
+            return;
+        }
+        if (event.key() == Key_Up) {
+            m_autocomplete_box->previous_suggestion();
+            return;
+        }
+        if (event.key() == Key_Return || event.key() == Key_Tab) {
+            m_autocomplete_box->apply_suggestion();
+            close_autocomplete();
+            return;
+        }
+    }
+
+    auto autocomplete_action = [this]() {
+        auto data = get_autocomplete_request_data();
+        if (data.has_value()) {
+            update_autocomplete(data.value());
+            if (m_autocomplete_in_focus)
+                show_autocomplete(data.value());
+        } else {
+            close_autocomplete();
+        }
+    };
+
     if (event.key() == Key_Control)
         m_holding_ctrl = true;
+
+    if (m_holding_ctrl && event.key() == Key_Space) {
+        autocomplete_action();
+    }
     GUI::TextEditor::keydown_event(event);
+
+    if (m_autocomplete_in_focus) {
+        autocomplete_action();
+    }
 }
 
 void Editor::keyup_event(GUI::KeyEvent& event)
@@ -421,4 +464,55 @@ void Editor::set_document(GUI::TextDocument& doc)
     GUI::TextEditor::set_document(doc);
 }
 
+Optional<Editor::AutoCompleteRequestData> Editor::get_autocomplete_request_data()
+{
+    auto highlighter = wrapper().editor().syntax_highlighter();
+    if (!highlighter)
+        return {};
+    auto& spans = document().spans();
+    for (size_t span_index = 2; span_index < spans.size(); ++span_index) {
+        auto& span = spans[span_index];
+        if (!span.range.contains(cursor())) {
+            continue;
+        }
+
+        if (highlighter->is_identifier(spans[span_index - 1].data)) {
+            auto completion_span = spans[span_index - 1];
+
+            auto adjusted_range = completion_span.range;
+            auto end_line_length = document().line(completion_span.range.end().line()).length();
+            adjusted_range.end().set_column(min(end_line_length, adjusted_range.end().column() + 1));
+            auto text_in_span = document().text_in_range(adjusted_range);
+
+            return AutoCompleteRequestData { completion_span.range.end(), text_in_span };
+        }
+    }
+    return {};
+}
+
+void Editor::update_autocomplete(const AutoCompleteRequestData& data)
+{
+    // TODO: Move this part to a language server component :)
+    auto suggestions = CppAutoComplete::get_suggestions(text(), data.position);
+    if (suggestions.is_empty()) {
+        close_autocomplete();
+        return;
+    }
+
+    m_autocomplete_box->update_suggestions(data.partial_input, move(suggestions));
+    m_autocomplete_in_focus = true;
+}
+
+void Editor::show_autocomplete(const AutoCompleteRequestData& data)
+{
+    auto suggestion_box_location = content_rect_for_position(data.position).bottom_right().translated(screen_relative_rect().top_left().translated(ruler_width(), 0).translated(10, 5));
+    m_autocomplete_box->show(suggestion_box_location);
+}
+
+void Editor::close_autocomplete()
+{
+    m_autocomplete_box->close();
+    m_autocomplete_in_focus = false;
+}
+
 }
diff --git a/DevTools/HackStudio/Editor.h b/DevTools/HackStudio/Editor.h
index e5f1cf335d..e034772c8d 100644
--- a/DevTools/HackStudio/Editor.h
+++ b/DevTools/HackStudio/Editor.h
@@ -26,9 +26,11 @@
 
 #pragma once
 
+#include "AutoCompleteBox.h"
 #include "CodeDocument.h"
 #include "Debugger/BreakpointCallback.h"
 #include <AK/Optional.h>
+#include <AK/OwnPtr.h>
 #include <LibGUI/TextEditor.h>
 #include <LibWeb/Forward.h>
 
@@ -78,15 +80,28 @@ private:
     static const Gfx::Bitmap& breakpoint_icon_bitmap();
     static const Gfx::Bitmap& current_position_icon_bitmap();
 
+    struct AutoCompleteRequestData {
+        GUI::TextPosition position;
+        String partial_input;
+    };
+
+    Optional<AutoCompleteRequestData> get_autocomplete_request_data();
+
+    void update_autocomplete(const AutoCompleteRequestData&);
+    void show_autocomplete(const AutoCompleteRequestData&);
+    void close_autocomplete();
+
     explicit Editor();
 
     RefPtr<GUI::Window> m_documentation_tooltip_window;
+    OwnPtr<AutoCompleteBox> m_autocomplete_box;
     RefPtr<Web::InProcessWebView> m_documentation_page_view;
     String m_last_parsed_token;
     GUI::TextPosition m_previous_text_position { 0, 0 };
     bool m_hovering_editor { false };
     bool m_hovering_link { false };
     bool m_holding_ctrl { false };
+    bool m_autocomplete_in_focus { false };
 };
 
 }
diff --git a/Libraries/LibGUI/TextEditor.h b/Libraries/LibGUI/TextEditor.h
index 0bdb68258a..175361487d 100644
--- a/Libraries/LibGUI/TextEditor.h
+++ b/Libraries/LibGUI/TextEditor.h
@@ -186,6 +186,8 @@ protected:
 
     TextPosition text_position_at(const Gfx::IntPoint&) const;
     bool ruler_visible() const { return m_ruler_visible; }
+    Gfx::IntRect content_rect_for_position(const TextPosition&) const;
+    int ruler_width() const;
 
 private:
     friend class TextDocumentLine;
@@ -231,7 +233,6 @@ private:
     Gfx::IntRect line_content_rect(size_t item_index) const;
     Gfx::IntRect line_widget_rect(size_t line_index) const;
     Gfx::IntRect cursor_content_rect() const;
-    Gfx::IntRect content_rect_for_position(const TextPosition&) const;
     void update_cursor();
     const NonnullOwnPtrVector<TextDocumentLine>& lines() const { return document().lines(); }
     NonnullOwnPtrVector<TextDocumentLine>& lines() { return document().lines(); }
@@ -239,7 +240,6 @@ private:
     const TextDocumentLine& line(size_t index) const { return document().line(index); }
     TextDocumentLine& current_line() { return line(m_cursor.line()); }
     const TextDocumentLine& current_line() const { return line(m_cursor.line()); }
-    int ruler_width() const;
     void toggle_selection_if_needed_for_event(const KeyEvent&);
     void delete_selection();
     void did_update_selection();