diff --git a/clang-tools-extra/clangd/clients/clangd-vscode/src/extension.ts b/clang-tools-extra/clangd/clients/clangd-vscode/src/extension.ts
--- a/clang-tools-extra/clangd/clients/clangd-vscode/src/extension.ts
+++ b/clang-tools-extra/clangd/clients/clangd-vscode/src/extension.ts
@@ -112,14 +112,6 @@
   const semanticHighlightingFeature =
       new semanticHighlighting.SemanticHighlightingFeature();
   clangdClient.registerFeature(semanticHighlightingFeature);
-  // The notification handler must be registered after the client is ready or
-  // the client will crash.
-  clangdClient.onReady().then(
-      () => clangdClient.onNotification(
-          semanticHighlighting.NotificationType,
-          semanticHighlightingFeature.handleNotification.bind(
-              semanticHighlightingFeature)));
-
   console.log('Clang Language Server is now active!');
   context.subscriptions.push(clangdClient.start());
   context.subscriptions.push(vscode.commands.registerCommand(
@@ -149,9 +141,14 @@
       clangdClient.onNotification(
           'textDocument/clangd.fileStatus',
           (fileStatus) => { status.onFileUpdated(fileStatus); });
+      clangdClient.onNotification(
+          semanticHighlighting.NotificationType,
+          semanticHighlightingFeature.handleNotification.bind(
+              semanticHighlightingFeature));
     } else if (newState == vscodelc.State.Stopped) {
       // Clear all cached statuses when clangd crashes.
       status.clear();
+      semanticHighlightingFeature.restartDispose();
     }
   })
   // An empty place holder for the activate command, otherwise we'll get an
diff --git a/clang-tools-extra/clangd/clients/clangd-vscode/src/semantic-highlighting.ts b/clang-tools-extra/clangd/clients/clangd-vscode/src/semantic-highlighting.ts
--- a/clang-tools-extra/clangd/clients/clangd-vscode/src/semantic-highlighting.ts
+++ b/clang-tools-extra/clangd/clients/clangd-vscode/src/semantic-highlighting.ts
@@ -56,6 +56,8 @@
   scopeLookupTable: string[][];
   // The object that applies the highlightings clangd sends.
   highlighter: Highlighter;
+  // Any disposables that should be cleaned up when clangd crashes.
+  private subscriptions: vscode.Disposable[] = [];
   fillClientCapabilities(capabilities: vscodelc.ClientCapabilities) {
     // Extend the ClientCapabilities type and add semantic highlighting
     // capability to the object.
@@ -87,15 +89,19 @@
     // Important that highlighter is created before the theme is loading as
     // otherwise it could try to update the themeRuleMatcher without the
     // highlighter being created.
-    this.highlighter = new Highlighter(this.scopeLookupTable);
+    if (!this.highlighter)
+      // If there already is a highlighter existing there is no need to create a
+      // new one, just reset and keep using it.
+      this.highlighter = new Highlighter(this.scopeLookupTable);
+    this.highlighter.clear();
     this.loadCurrentTheme();
     // Event handling for handling with TextDocuments/Editors lifetimes.
-    vscode.window.onDidChangeVisibleTextEditors(
+    this.subscriptions.push(vscode.window.onDidChangeVisibleTextEditors(
         (editors: vscode.TextEditor[]) =>
             editors.forEach((e) => this.highlighter.applyHighlights(
-                                e.document.uri.toString())));
-    vscode.workspace.onDidCloseTextDocument(
-        (doc) => this.highlighter.removeFileHighlightings(doc.uri.toString()));
+                                e.document.uri.toString()))));
+    this.subscriptions.push(vscode.workspace.onDidCloseTextDocument(
+        (doc) => this.highlighter.removeFileHighlightings(doc.uri.toString())));
   }
 
   handleNotification(params: SemanticHighlightingParams) {
@@ -103,6 +109,12 @@
         (line) => ({line : line.line, tokens : decodeTokens(line.tokens)}));
     this.highlighter.highlight(params.textDocument.uri, lines);
   }
+  // Disposes of any resources that are not reused when if initialize is called
+  // again.
+  public restartDispose() {
+    this.subscriptions.forEach((d) => d.dispose());
+    this.subscriptions = [];
+  }
 }
 
 // Converts a string of base64 encoded tokens into the corresponding array of
@@ -138,6 +150,7 @@
   constructor(scopeLookupTable: string[][]) {
     this.scopeLookupTable = scopeLookupTable;
   }
+  public clear() { this.files.clear(); }
   // This function must be called at least once or no highlightings will be
   // done. Sets the theme that is used when highlighting. Also triggers a
   // recolorization for all current highlighters. Should be called whenever the
@@ -174,6 +187,27 @@
     this.applyHighlights(fileUri);
   }
 
+  // Applies all the highlightings currently stored for a file with fileUri.
+  public applyHighlights(fileUri: string) {
+    if (!this.files.has(fileUri))
+      // There are no highlightings for this file, must return early or will get
+      // out of bounds when applying the decorations below.
+      return;
+    if (!this.decorationTypes.length)
+      // Can't apply any decorations when there is no theme loaded.
+      return;
+    // This must always do a full re-highlighting due to the fact that
+    // TextEditorDecorationType are very expensive to create (which makes
+    // incremental updates infeasible). For this reason one
+    // TextEditorDecorationType is used per scope.
+    const ranges = this.getDecorationRanges(fileUri);
+    vscode.window.visibleTextEditors.forEach((e) => {
+      if (e.document.uri.toString() !== fileUri)
+        return;
+      this.decorationTypes.forEach((d, i) => e.setDecorations(d, ranges[i]));
+    });
+  }
+
   // Called when a text document is closed. Removes any highlighting entries for
   // the text document that was closed.
   public removeFileHighlightings(fileUri: string) {
@@ -207,27 +241,6 @@
     });
     return decorations;
   }
-
-  // Applies all the highlightings currently stored for a file with fileUri.
-  public applyHighlights(fileUri: string) {
-    if (!this.files.has(fileUri))
-      // There are no highlightings for this file, must return early or will get
-      // out of bounds when applying the decorations below.
-      return;
-    if (!this.decorationTypes.length)
-      // Can't apply any decorations when there is no theme loaded.
-      return;
-    // This must always do a full re-highlighting due to the fact that
-    // TextEditorDecorationType are very expensive to create (which makes
-    // incremental updates infeasible). For this reason one
-    // TextEditorDecorationType is used per scope.
-    const ranges = this.getDecorationRanges(fileUri);
-    vscode.window.visibleTextEditors.forEach((e) => {
-      if (e.document.uri.toString() !== fileUri)
-        return;
-      this.decorationTypes.forEach((d, i) => e.setDecorations(d, ranges[i]));
-    });
-  }
 }
 
 // A rule for how to color TextMate scopes.
diff --git a/clang-tools-extra/clangd/clients/clangd-vscode/test/semantic-highlighting.test.ts b/clang-tools-extra/clangd/clients/clangd-vscode/test/semantic-highlighting.test.ts
--- a/clang-tools-extra/clangd/clients/clangd-vscode/test/semantic-highlighting.test.ts
+++ b/clang-tools-extra/clangd/clients/clangd-vscode/test/semantic-highlighting.test.ts
@@ -107,7 +107,8 @@
     highlighter.highlight('file1', []);
     assert.deepEqual(highlighter.applicationUriHistory, [ 'file1' ]);
     highlighter.initialize(tm);
-    assert.deepEqual(highlighter.applicationUriHistory, [ 'file1', 'file1', 'file2' ]);
+    assert.deepEqual(highlighter.applicationUriHistory,
+                     [ 'file1', 'file1', 'file2' ]);
     // Groups decorations into the scopes used.
     let highlightingsInLine: semanticHighlighting.SemanticHighlightingLine[] = [
       {