diff --git a/Source/WTF/Scripts/Preferences/UnifiedWebPreferences.yaml b/Source/WTF/Scripts/Preferences/UnifiedWebPreferences.yaml
index 7ee965c3cf14b..876215ea6ba28 100644
--- a/Source/WTF/Scripts/Preferences/UnifiedWebPreferences.yaml
+++ b/Source/WTF/Scripts/Preferences/UnifiedWebPreferences.yaml
@@ -8326,6 +8326,21 @@ WriteRichTextDataWhenCopyingOrDragging:
     WebCore:
       default: true
 
+WritingSuggestionsAttributeEnabled:
+  type: bool
+  status: stable
+  category: dom
+  humanReadableName: "Writing Suggestions"
+  humanReadableDescription: "Enable the writingsuggestions attribute"
+  condition: ENABLE(WRITING_SUGGESTIONS)
+  defaultValue:
+    WebKitLegacy:
+      default: true
+    WebKit:
+      default: true
+    WebCore:
+      default: true
+
 ZoomOnDoubleTapWhenRoot:
   type: bool
   status: internal
diff --git a/Source/WTF/wtf/PlatformEnable.h b/Source/WTF/wtf/PlatformEnable.h
index 88f2ed08021f9..f2db0b5dc3935 100644
--- a/Source/WTF/wtf/PlatformEnable.h
+++ b/Source/WTF/wtf/PlatformEnable.h
@@ -995,3 +995,8 @@
     && USE(LINEARMEDIAKIT)
 #define ENABLE_LINEAR_MEDIA_PLAYER 0
 #endif
+
+#if !defined(ENABLE_WRITING_SUGGESTIONS) \
+    && (PLATFORM(COCOA) && HAVE(INLINE_PREDICTIONS))
+#define ENABLE_WRITING_SUGGESTIONS 1
+#endif
diff --git a/Source/WebCore/dom/Element.cpp b/Source/WebCore/dom/Element.cpp
index 29ab5763cac38..eb6c5649df0e2 100644
--- a/Source/WebCore/dom/Element.cpp
+++ b/Source/WebCore/dom/Element.cpp
@@ -80,8 +80,10 @@
 #include "HTMLScriptElement.h"
 #include "HTMLSelectElement.h"
 #include "HTMLTemplateElement.h"
+#include "HTMLTextAreaElement.h"
 #include "IdChangeInvalidation.h"
 #include "IdTargetObserverRegistry.h"
+#include "InputType.h"
 #include "InspectorInstrumentation.h"
 #include "JSDOMPromiseDeferred.h"
 #include "JSLazyEventListener.h"
@@ -4752,6 +4754,53 @@ bool Element::isSpellCheckingEnabled() const
     return true;
 }
 
+bool Element::isWritingSuggestionsEnabled() const
+{
+    // If none of the following conditions are true, then return `false`.
+
+    // `element` is an `input` element whose `type` attribute is in either the
+    // `Text`, `Search`, `URL`, `Email` state and is `mutable`.
+    auto isEligibleInputElement = [&] {
+        RefPtr input = dynamicDowncast<HTMLInputElement>(*this);
+        if (!input)
+            return false;
+
+        return !input->isDisabledFormControl() && input->supportsWritingSuggestions();
+    };
+
+    // `element` is a `textarea` element that is `mutable`.
+    auto isEligibleTextArea = [&] {
+        RefPtr textArea = dynamicDowncast<HTMLTextAreaElement>(*this);
+        if (!textArea)
+            return false;
+
+        return !textArea->isDisabledFormControl();
+    };
+
+    // `element` is an `editing host` or is `editable`.
+
+    if (!isEligibleInputElement() && !isEligibleTextArea() && !hasEditableStyle())
+        return false;
+
+    // If `element` has an 'inclusive ancestor' with a `writingsuggestions` content attribute that's
+    // not in the `default` state and the nearest such ancestor's `writingsuggestions` content attribute
+    // is in the `false` state, then return `false`.
+
+    for (auto* ancestor = this; ancestor; ancestor = ancestor->parentElementInComposedTree()) {
+        auto& value = ancestor->attributeWithoutSynchronization(HTMLNames::writingsuggestionsAttr);
+
+        if (value.isNull())
+            continue;
+        if (value.isEmpty() || equalLettersIgnoringASCIICase(value, "true"_s))
+            return true;
+        if (equalLettersIgnoringASCIICase(value, "false"_s))
+            return false;
+    }
+
+    // Otherwise, return `true`.
+    return true;
+}
+
 #if ASSERT_ENABLED
 bool Element::fastAttributeLookupAllowed(const QualifiedName& name) const
 {
diff --git a/Source/WebCore/dom/Element.h b/Source/WebCore/dom/Element.h
index a510ddb99f81e..1d74cdd3923c9 100644
--- a/Source/WebCore/dom/Element.h
+++ b/Source/WebCore/dom/Element.h
@@ -629,6 +629,7 @@ class Element : public ContainerNode {
 #endif
 
     bool isSpellCheckingEnabled() const;
+    WEBCORE_EXPORT bool isWritingSuggestionsEnabled() const;
 
     inline bool hasID() const;
     inline bool hasClass() const;
diff --git a/Source/WebCore/editing/VisibleSelection.cpp b/Source/WebCore/editing/VisibleSelection.cpp
index 69a8dd3bc327d..43d8f6216acf2 100644
--- a/Source/WebCore/editing/VisibleSelection.cpp
+++ b/Source/WebCore/editing/VisibleSelection.cpp
@@ -687,6 +687,21 @@ bool VisibleSelection::isInPasswordField() const
     return textControl && textControl->isPasswordField();
 }
 
+bool VisibleSelection::canEnableWritingSuggestions() const
+{
+    RefPtr containerNode = start().containerNode();
+    if (!containerNode)
+        return false;
+
+    if (RefPtr element = dynamicDowncast<Element>(containerNode.get()))
+        return element->isWritingSuggestionsEnabled();
+
+    if (RefPtr element = containerNode->parentElement())
+        return element->isWritingSuggestionsEnabled();
+
+    return false;
+}
+
 bool VisibleSelection::isInAutoFilledAndViewableField() const
 {
     if (RefPtr input = dynamicDowncast<HTMLInputElement>(enclosingTextFormControl(start())))
diff --git a/Source/WebCore/editing/VisibleSelection.h b/Source/WebCore/editing/VisibleSelection.h
index 60c9998df33fe..0717b381a1441 100644
--- a/Source/WebCore/editing/VisibleSelection.h
+++ b/Source/WebCore/editing/VisibleSelection.h
@@ -118,6 +118,8 @@ class VisibleSelection {
     WEBCORE_EXPORT bool isInPasswordField() const;
     WEBCORE_EXPORT bool isInAutoFilledAndViewableField() const;
 
+    WEBCORE_EXPORT bool canEnableWritingSuggestions() const;
+
     WEBCORE_EXPORT static Position adjustPositionForEnd(const Position& currentPosition, Node* startContainerNode);
     WEBCORE_EXPORT static Position adjustPositionForStart(const Position& currentPosition, Node* startContainerNode);
 
diff --git a/Source/WebCore/html/HTMLAttributeNames.in b/Source/WebCore/html/HTMLAttributeNames.in
index dc81afe2f24bf..b53f68f2216c3 100644
--- a/Source/WebCore/html/HTMLAttributeNames.in
+++ b/Source/WebCore/html/HTMLAttributeNames.in
@@ -431,6 +431,7 @@ webkitdirectory
 webkitdropzone
 width
 wrap
+writingsuggestions
 x-apple-data-detectors
 x-apple-data-detectors-result
 x-apple-data-detectors-type
diff --git a/Source/WebCore/html/HTMLElement.cpp b/Source/WebCore/html/HTMLElement.cpp
index 27e8cad0ea533..e46ec7fd3876e 100644
--- a/Source/WebCore/html/HTMLElement.cpp
+++ b/Source/WebCore/html/HTMLElement.cpp
@@ -731,6 +731,16 @@ void HTMLElement::setSpellcheck(bool enable)
     setAttributeWithoutSynchronization(spellcheckAttr, enable ? trueAtom() : falseAtom());
 }
 
+bool HTMLElement::writingsuggestions() const
+{
+    return isWritingSuggestionsEnabled();
+}
+
+void HTMLElement::setWritingsuggestions(bool enable)
+{
+    setAttributeWithoutSynchronization(writingsuggestionsAttr, enable ? trueAtom() : falseAtom());
+}
+
 void HTMLElement::effectiveSpellcheckAttributeChanged(bool newValue)
 {
     for (auto it = descendantsOfType<HTMLElement>(*this).begin(); it;) {
diff --git a/Source/WebCore/html/HTMLElement.h b/Source/WebCore/html/HTMLElement.h
index 1b2aff9aee73b..01ee460c27754 100644
--- a/Source/WebCore/html/HTMLElement.h
+++ b/Source/WebCore/html/HTMLElement.h
@@ -84,6 +84,9 @@ class HTMLElement : public StyledElement {
     WEBCORE_EXPORT bool spellcheck() const;
     WEBCORE_EXPORT void setSpellcheck(bool);
 
+    WEBCORE_EXPORT bool writingsuggestions() const;
+    WEBCORE_EXPORT void setWritingsuggestions(bool);
+
     WEBCORE_EXPORT bool translate() const;
     WEBCORE_EXPORT void setTranslate(bool);
 
diff --git a/Source/WebCore/html/HTMLElement.idl b/Source/WebCore/html/HTMLElement.idl
index 755368a5ab84a..d6aaf324d5b59 100644
--- a/Source/WebCore/html/HTMLElement.idl
+++ b/Source/WebCore/html/HTMLElement.idl
@@ -69,6 +69,8 @@
 
     // Non-standard: We are the only browser to support this now that Blink dropped it (http://crbug.com/688943).
     [CEReactions=Needed, Reflect] attribute DOMString webkitdropzone;
+
+    [Conditional=WRITING_SUGGESTIONS, CEReactions=Needed] attribute boolean writingsuggestions;
 };
 
 HTMLElement includes GlobalEventHandlers;
diff --git a/Source/WebCore/html/HTMLInputElement.cpp b/Source/WebCore/html/HTMLInputElement.cpp
index 426db6c96a71c..5109ff1cc0879 100644
--- a/Source/WebCore/html/HTMLInputElement.cpp
+++ b/Source/WebCore/html/HTMLInputElement.cpp
@@ -1039,6 +1039,18 @@ bool HTMLInputElement::isTextType() const
     return m_inputType->isTextType();
 }
 
+bool HTMLInputElement::supportsWritingSuggestions() const
+{
+    static constexpr OptionSet<InputType::Type> allowedTypes = {
+        InputType::Type::Text,
+        InputType::Type::Search,
+        InputType::Type::URL,
+        InputType::Type::Email,
+    };
+
+    return allowedTypes.contains(m_inputType->type());
+}
+
 void HTMLInputElement::setDefaultCheckedState(bool isDefaultChecked)
 {
     if (m_isDefaultChecked == isDefaultChecked)
diff --git a/Source/WebCore/html/HTMLInputElement.h b/Source/WebCore/html/HTMLInputElement.h
index f511366a778ae..4352fab7d2432 100644
--- a/Source/WebCore/html/HTMLInputElement.h
+++ b/Source/WebCore/html/HTMLInputElement.h
@@ -157,6 +157,7 @@ class HTMLInputElement : public HTMLTextFormControlElement {
     // isTextField && !isPasswordField.
     WEBCORE_EXPORT bool isText() const;
     bool isTextType() const;
+    bool supportsWritingSuggestions() const;
     WEBCORE_EXPORT bool isEmailField() const;
     WEBCORE_EXPORT bool isFileUpload() const;
     bool isImageButton() const;
diff --git a/Source/WebKit/Shared/EditorState.cpp b/Source/WebKit/Shared/EditorState.cpp
index ecb5844f9aa90..0e7ab2e8c0c4b 100644
--- a/Source/WebKit/Shared/EditorState.cpp
+++ b/Source/WebKit/Shared/EditorState.cpp
@@ -75,6 +75,8 @@ TextStream& operator<<(TextStream& ts, const EditorState& editorState)
             ts.dumpProperty("enclosingListType", enumToUnderlyingType(editorState.postLayoutData->enclosingListType));
         if (editorState.postLayoutData->baseWritingDirection != WebCore::WritingDirection::Natural)
             ts.dumpProperty("baseWritingDirection", static_cast<uint8_t>(editorState.postLayoutData->baseWritingDirection));
+        if (editorState.postLayoutData->canEnableWritingSuggestions)
+            ts.dumpProperty("canEnableWritingSuggestions", editorState.postLayoutData->canEnableWritingSuggestions);
 #endif // PLATFORM(COCOA)
 #if PLATFORM(IOS_FAMILY)
         if (editorState.postLayoutData->markedText.length())
diff --git a/Source/WebKit/Shared/EditorState.h b/Source/WebKit/Shared/EditorState.h
index 907d8d53b88e4..7f8104aded87e 100644
--- a/Source/WebKit/Shared/EditorState.h
+++ b/Source/WebKit/Shared/EditorState.h
@@ -95,6 +95,7 @@ struct EditorState {
         ListType enclosingListType { ListType::None };
         WebCore::WritingDirection baseWritingDirection { WebCore::WritingDirection::Natural };
         bool editableRootIsTransparentOrFullyClipped { false };
+        bool canEnableWritingSuggestions { false };
 #endif
 #if PLATFORM(IOS_FAMILY)
         String markedText;
diff --git a/Source/WebKit/Shared/EditorState.serialization.in b/Source/WebKit/Shared/EditorState.serialization.in
index d2f2a49055783..24bf05b03dec6 100644
--- a/Source/WebKit/Shared/EditorState.serialization.in
+++ b/Source/WebKit/Shared/EditorState.serialization.in
@@ -70,6 +70,7 @@ struct WebKit::EditorState {
     WebKit::ListType enclosingListType;
     WebCore::WritingDirection baseWritingDirection;
     bool editableRootIsTransparentOrFullyClipped;
+    bool canEnableWritingSuggestions;
 #endif
 #if PLATFORM(IOS_FAMILY)
     String markedText;
diff --git a/Source/WebKit/Shared/FocusedElementInformation.h b/Source/WebKit/Shared/FocusedElementInformation.h
index 010cc2ed9e03d..c70cb6fa6bb59 100644
--- a/Source/WebKit/Shared/FocusedElementInformation.h
+++ b/Source/WebKit/Shared/FocusedElementInformation.h
@@ -134,6 +134,7 @@ struct FocusedElementInformation {
     bool hasEverBeenPasswordField { false };
     bool shouldSynthesizeKeyEventsForEditing { false };
     bool isSpellCheckingEnabled { true };
+    bool isWritingSuggestionsEnabled { false };
     bool shouldAvoidResizingWhenInputViewBoundsChange { false };
     bool shouldAvoidScrollingWhenFocusedContentIsVisible { false };
     bool shouldUseLegacySelectPopoverDismissalBehaviorInDataActivation { false };
diff --git a/Source/WebKit/Shared/FocusedElementInformation.serialization.in b/Source/WebKit/Shared/FocusedElementInformation.serialization.in
index 5e899fd6fa7d3..f8cd77fb21e9d 100644
--- a/Source/WebKit/Shared/FocusedElementInformation.serialization.in
+++ b/Source/WebKit/Shared/FocusedElementInformation.serialization.in
@@ -104,6 +104,7 @@ enum class WebKit::InputType : uint8_t {
     bool hasEverBeenPasswordField;
     bool shouldSynthesizeKeyEventsForEditing;
     bool isSpellCheckingEnabled;
+    bool isWritingSuggestionsEnabled;
     bool shouldAvoidResizingWhenInputViewBoundsChange;
     bool shouldAvoidScrollingWhenFocusedContentIsVisible;
     bool shouldUseLegacySelectPopoverDismissalBehaviorInDataActivation;
diff --git a/Source/WebKit/UIProcess/ios/WKContentViewInteraction.mm b/Source/WebKit/UIProcess/ios/WKContentViewInteraction.mm
index 2045dcb3cff72..4e78e32743107 100644
--- a/Source/WebKit/UIProcess/ios/WKContentViewInteraction.mm
+++ b/Source/WebKit/UIProcess/ios/WKContentViewInteraction.mm
@@ -6915,7 +6915,7 @@ - (void)_updateTextInputTraits:(id<UITextInputTraits>)traits
         privateTraits.shortcutConversionType = _focusedElementInformation.elementType == WebKit::InputType::Password ? UITextShortcutConversionTypeNo : UITextShortcutConversionTypeDefault;
 
 #if HAVE(INLINE_PREDICTIONS)
-    traits.inlinePredictionType = (self.webView.configuration.allowsInlinePredictions || _page->preferences().inlinePredictionsInAllEditableElementsEnabled()) ? UITextInlinePredictionTypeDefault : UITextInlinePredictionTypeNo;
+    traits.inlinePredictionType = (self.webView.configuration.allowsInlinePredictions || _page->preferences().inlinePredictionsInAllEditableElementsEnabled() || _focusedElementInformation.isWritingSuggestionsEnabled) ? UITextInlinePredictionTypeDefault : UITextInlinePredictionTypeNo;
 #endif
 
     [self _updateTextInputTraitsForInteractionTintColor];
diff --git a/Source/WebKit/UIProcess/mac/WebViewImpl.mm b/Source/WebKit/UIProcess/mac/WebViewImpl.mm
index cd8f553e536a8..3a9bb887bb59d 100644
--- a/Source/WebKit/UIProcess/mac/WebViewImpl.mm
+++ b/Source/WebKit/UIProcess/mac/WebViewImpl.mm
@@ -3210,8 +3210,6 @@ static String commandNameForSelector(SEL selector)
 std::optional<EditorState::PostLayoutData> WebViewImpl::postLayoutDataForContentEditable()
 {
     const EditorState& editorState = m_page->editorState();
-    if (!editorState.isContentEditable)
-        return std::nullopt;
 
     // FIXME: It's pretty lame that we have to depend on the most recent EditorState having post layout data,
     // and that we just bail if it is missing.
@@ -5195,6 +5193,14 @@ static BOOL shouldUseHighlightsForMarkedText(NSAttributedString *string)
 #if HAVE(INLINE_PREDICTIONS)
 bool WebViewImpl::allowsInlinePredictions() const
 {
+    const EditorState& editorState = m_page->editorState();
+
+    if (editorState.hasPostLayoutData() && editorState.postLayoutData->canEnableWritingSuggestions)
+        return NSSpellChecker.isAutomaticInlineCompletionEnabled;
+
+    if (!editorState.isContentEditable)
+        return false;
+
     if (!inlinePredictionsEnabled() && !m_page->preferences().inlinePredictionsInAllEditableElementsEnabled())
         return false;
 
diff --git a/Source/WebKit/WebProcess/WebPage/Cocoa/WebPageCocoa.mm b/Source/WebKit/WebProcess/WebPage/Cocoa/WebPageCocoa.mm
index ae43f1a4698bf..cefe2e2345ab8 100644
--- a/Source/WebKit/WebProcess/WebPage/Cocoa/WebPageCocoa.mm
+++ b/Source/WebKit/WebProcess/WebPage/Cocoa/WebPageCocoa.mm
@@ -584,6 +584,8 @@
         }
 
         postLayoutData.baseWritingDirection = frame.editor().baseWritingDirectionForSelectionStart();
+
+        postLayoutData.canEnableWritingSuggestions = selection.canEnableWritingSuggestions();
     }
 
     if (RefPtr editableRootOrFormControl = enclosingTextFormControl(selection.start()) ?: selection.rootEditableElement()) {
diff --git a/Source/WebKit/WebProcess/WebPage/ios/WebPageIOS.mm b/Source/WebKit/WebProcess/WebPage/ios/WebPageIOS.mm
index a7fd723127c0d..104410c82c8c3 100644
--- a/Source/WebKit/WebProcess/WebPage/ios/WebPageIOS.mm
+++ b/Source/WebKit/WebProcess/WebPage/ios/WebPageIOS.mm
@@ -3550,6 +3550,8 @@ static void handleAnimationActions(Element& element, uint32_t action)
     if (htmlElement)
         information.isSpellCheckingEnabled = htmlElement->spellcheck();
 
+    information.isWritingSuggestionsEnabled = focusedElement->isWritingSuggestionsEnabled();
+
     if (RefPtr formControlElement = dynamicDowncast<HTMLFormControlElement>(focusedElement))
         information.isFocusingWithValidationMessage = formControlElement->isFocusingWithValidationMessage();
 
diff --git a/Tools/TestWebKitAPI/SourcesCocoa.txt b/Tools/TestWebKitAPI/SourcesCocoa.txt
index d4dd36e81732a..cdcced1ae8cc8 100644
--- a/Tools/TestWebKitAPI/SourcesCocoa.txt
+++ b/Tools/TestWebKitAPI/SourcesCocoa.txt
@@ -353,6 +353,7 @@ Tests/WebKitCocoa/WebSQLBasics.mm
 Tests/WebKitCocoa/WebSocket.mm
 Tests/WebKitCocoa/WebsiteDataStoreCustomPaths.mm
 Tests/WebKitCocoa/WebsitePolicies.mm
+Tests/WebKitCocoa/WritingSuggestions.mm
 Tests/WebKitCocoa/YoutubeReplacementPlugin.mm
 Tests/WebKitCocoa/_WKInputDelegate.mm
 Tests/WebKitCocoa/_WKWebAuthenticationPanel.mm
diff --git a/Tools/TestWebKitAPI/TestWebKitAPI.xcodeproj/project.pbxproj b/Tools/TestWebKitAPI/TestWebKitAPI.xcodeproj/project.pbxproj
index 7f328039f3c18..2f26853d986d1 100644
--- a/Tools/TestWebKitAPI/TestWebKitAPI.xcodeproj/project.pbxproj
+++ b/Tools/TestWebKitAPI/TestWebKitAPI.xcodeproj/project.pbxproj
@@ -2013,6 +2013,7 @@
 		0711DF51226A95FB003DD2F7 /* AVFoundationSoftLinkTest.mm */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.objcpp; path = AVFoundationSoftLinkTest.mm; sourceTree = "<group>"; };
 		07137049265320E500CA2C9A /* AudioBufferSize.mm */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.objcpp; path = AudioBufferSize.mm; sourceTree = "<group>"; };
 		0721D4582838295400A95853 /* start-offset.ts */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.typescript; path = "start-offset.ts"; sourceTree = "<group>"; };
+		07338E042B7433A400F949EB /* WritingSuggestions.mm */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.objcpp; path = WritingSuggestions.mm; sourceTree = "<group>"; };
 		0738012E275EADAB000FA77C /* GetDisplayMediaWindowAndScreen.mm */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.objcpp; path = GetDisplayMediaWindowAndScreen.mm; sourceTree = "<group>"; };
 		0746645722FF62D000E3451A /* AccessibilityTestSupportProtocol.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = AccessibilityTestSupportProtocol.h; sourceTree = "<group>"; };
 		0746645822FF630500E3451A /* AccessibilityTestPlugin.mm */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.cpp.objcpp; path = AccessibilityTestPlugin.mm; sourceTree = "<group>"; };
@@ -4337,6 +4338,7 @@
 				9984FACA1CFFAEEE008D198C /* WKWebViewTextInput.mm */,
 				95A524942581A10D00461FE9 /* WKWebViewThemeColor.mm */,
 				953ABB3425C0D681004C8B73 /* WKWebViewUnderPageBackgroundColor.mm */,
+				07338E042B7433A400F949EB /* WritingSuggestions.mm */,
 				465A08FD280096F80028FD0E /* YoutubeReplacementPlugin.mm */,
 			);
 			name = "WebKit Cocoa";
diff --git a/Tools/TestWebKitAPI/Tests/WebKitCocoa/WritingSuggestions.mm b/Tools/TestWebKitAPI/Tests/WebKitCocoa/WritingSuggestions.mm
new file mode 100644
index 0000000000000..19ccf0c74a6bb
--- /dev/null
+++ b/Tools/TestWebKitAPI/Tests/WebKitCocoa/WritingSuggestions.mm
@@ -0,0 +1,120 @@
+/*
+ * Copyright (C) 2017 Apple Inc. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
+ * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
+ * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
+ * THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#import "config.h"
+
+// FIXME: Get these tests to run on other platforms.
+#if PLATFORM(IOS_FAMILY) && ENABLE(WRITING_SUGGESTIONS)
+
+#import "PlatformUtilities.h"
+#import "Test.h"
+#import "TestInputDelegate.h"
+#import "TestNavigationDelegate.h"
+#import "TestProtocol.h"
+#import "TestResourceLoadDelegate.h"
+#import "TestWKWebView.h"
+#import "UIKitSPIForTesting.h"
+#import "WKWebViewConfigurationExtras.h"
+#import <WebKit/_WKResourceLoadInfo.h>
+#import <WebKit/_WKWebsiteDataStoreConfiguration.h>
+
+@interface WritingSuggestionsWebAPIWKWebView : TestWKWebView
+
+- (void)focusElementAndEnsureEditorStateUpdate:(NSString *)element;
+
+@end
+
+@implementation WritingSuggestionsWebAPIWKWebView {
+    RetainPtr<TestInputDelegate> _inputDelegate;
+}
+
+- (instancetype)initWithHTMLString:(NSString *)string
+{
+    auto configuration = [WKWebViewConfiguration _test_configurationWithTestPlugInClassName:@"WebProcessPlugInWithInternals" configureJSCForTesting:YES];
+
+    if (!(self = [super initWithFrame:CGRectMake(0, 0, 320, 568) configuration:configuration]))
+        return nil;
+
+    _inputDelegate = adoptNS([[TestInputDelegate alloc] init]);
+    [_inputDelegate setFocusStartsInputSessionPolicyHandler:[&] (WKWebView *, id<_WKFocusedElementInfo>) -> _WKFocusStartsInputSessionPolicy {
+        return _WKFocusStartsInputSessionPolicyAllow;
+    }];
+    [self _setInputDelegate:_inputDelegate.get()];
+
+    [self synchronouslyLoadHTMLString:string];
+
+    return self;
+}
+
+- (void)focusElementAndEnsureEditorStateUpdate:(NSString *)element
+{
+    NSString *script = [NSString stringWithFormat:@"%@.focus()", element];
+    [self evaluateJavaScriptAndWaitForInputSessionToChange:script];
+    [self waitForNextPresentationUpdate];
+}
+
+@end
+
+TEST(WritingSuggestionsWebAPI, DefaultState)
+{
+    auto webView = adoptNS([[WritingSuggestionsWebAPIWKWebView alloc] initWithHTMLString:@"<body><div id='div' contenteditable>This is some text.</div></body>"]);
+    [webView focusElementAndEnsureEditorStateUpdate:@"document.getElementById('div')"];
+
+    EXPECT_EQ(UITextInlinePredictionTypeDefault, [webView effectiveTextInputTraits].inlinePredictionType);
+}
+
+TEST(WritingSuggestionsWebAPI, DefaultStateWithInput)
+{
+    auto webView = adoptNS([[WritingSuggestionsWebAPIWKWebView alloc] initWithHTMLString:@"<body><input id='input' type='text'></input></body>"]);
+    [webView focusElementAndEnsureEditorStateUpdate:@"document.getElementById('input')"];
+
+    EXPECT_EQ(UITextInlinePredictionTypeDefault, [webView effectiveTextInputTraits].inlinePredictionType);
+}
+
+TEST(WritingSuggestionsWebAPI, ExplicitlyEnabled)
+{
+    auto webView = adoptNS([[WritingSuggestionsWebAPIWKWebView alloc] initWithHTMLString:@"<body><div id='div' contenteditable writingsuggestions='true'>This is some text.</div></body>"]);
+    [webView focusElementAndEnsureEditorStateUpdate:@"document.getElementById('div')"];
+
+    EXPECT_EQ(UITextInlinePredictionTypeDefault, [webView effectiveTextInputTraits].inlinePredictionType);
+}
+
+TEST(WritingSuggestionsWebAPI, ExplicitlyDisabled)
+{
+    auto webView = adoptNS([[WritingSuggestionsWebAPIWKWebView alloc] initWithHTMLString:@"<body><div id='div' contenteditable writingsuggestions='false'>This is some text.</div></body>"]);
+    [webView focusElementAndEnsureEditorStateUpdate:@"document.getElementById('div')"];
+
+    EXPECT_EQ(UITextInlinePredictionTypeNo, [webView effectiveTextInputTraits].inlinePredictionType);
+}
+
+TEST(WritingSuggestionsWebAPI, ExplicitlyDisabledOnParent)
+{
+    auto webView = adoptNS([[WritingSuggestionsWebAPIWKWebView alloc] initWithHTMLString:@"<body><div writingsuggestions='false'><div id='div' contenteditable>This is some text.</div></div></body>"]);
+    [webView focusElementAndEnsureEditorStateUpdate:@"document.getElementById('div')"];
+
+    EXPECT_EQ(UITextInlinePredictionTypeNo, [webView effectiveTextInputTraits].inlinePredictionType);
+}
+
+#endif