diff --git a/src/generic/CodeEditor.tsx b/src/generic/CodeEditor.tsx
new file mode 100644
index 0000000000..f98c0bd768
--- /dev/null
+++ b/src/generic/CodeEditor.tsx
@@ -0,0 +1,55 @@
+/* eslint-disable import/prefer-default-export */
+import React from 'react';
+import { basicSetup, EditorView } from 'codemirror';
+import { EditorState, Compartment } from '@codemirror/state';
+import { xml } from '@codemirror/lang-xml';
+
+export type EditorAccessor = EditorView;
+
+interface Props {
+  readOnly?: boolean;
+  children?: string;
+  editorRef?: React.MutableRefObject<EditorAccessor | undefined>;
+}
+
+export const CodeEditor: React.FC<Props> = ({
+  readOnly = false,
+  children = '',
+  editorRef,
+}) => {
+  const divRef = React.useRef<HTMLDivElement>(null);
+  const language = React.useMemo(() => new Compartment(), []);
+  const tabSize = React.useMemo(() => new Compartment(), []);
+
+  React.useEffect(() => {
+    if (!divRef.current) { return; }
+    const state = EditorState.create({
+      doc: children,
+      extensions: [
+        basicSetup,
+        language.of(xml()),
+        tabSize.of(EditorState.tabSize.of(2)),
+        EditorState.readOnly.of(readOnly),
+      ],
+    });
+
+    const view = new EditorView({
+      state,
+      parent: divRef.current,
+    });
+    if (editorRef) {
+      // eslint-disable-next-line no-param-reassign
+      editorRef.current = view;
+    }
+    // eslint-disable-next-line consistent-return
+    return () => {
+      if (editorRef) {
+        // eslint-disable-next-line no-param-reassign
+        editorRef.current = undefined;
+      }
+      view.destroy(); // Clean up
+    };
+  }, [divRef.current, readOnly, editorRef]);
+
+  return <div ref={divRef} />;
+};
diff --git a/src/library-authoring/component-info/ComponentAdvancedInfo.tsx b/src/library-authoring/component-info/ComponentAdvancedInfo.tsx
index f45d3a249f..38eccb2a07 100644
--- a/src/library-authoring/component-info/ComponentAdvancedInfo.tsx
+++ b/src/library-authoring/component-info/ComponentAdvancedInfo.tsx
@@ -1,10 +1,16 @@
 /* eslint-disable import/prefer-default-export */
 import React from 'react';
-import { Collapsible } from '@openedx/paragon';
+import {
+  Button,
+  Collapsible,
+  OverlayTrigger,
+  Tooltip,
+} from '@openedx/paragon';
 import { FormattedMessage, useIntl } from '@edx/frontend-platform/i18n';
 
 import { LoadingSpinner } from '../../generic/Loading';
-import { useXBlockOLX } from '../data/apiHooks';
+import { CodeEditor, EditorAccessor } from '../../generic/CodeEditor';
+import { useUpdateXBlockOLX, useXBlockOLX } from '../data/apiHooks';
 import messages from './messages';
 
 interface Props {
@@ -13,7 +19,27 @@ interface Props {
 
 export const ComponentAdvancedInfo: React.FC<Props> = ({ usageKey }) => {
   const intl = useIntl();
+  // TODO: hide the "Edit" button if the library is read only
   const { data: olx, isLoading: isOLXLoading } = useXBlockOLX(usageKey);
+  const editorRef = React.useRef<EditorAccessor | undefined>(undefined);
+  const [isEditingOLX, setEditingOLX] = React.useState(false);
+  const olxUpdater = useUpdateXBlockOLX(usageKey);
+  const updateOlx = React.useCallback(() => {
+    const newOLX = editorRef.current?.state.doc.toString();
+    if (!newOLX) {
+      /* istanbul ignore next */
+      throw new Error('Unable to get OLX string from codemirror.'); // Shouldn't happen.
+    }
+    olxUpdater.mutateAsync(newOLX).catch(err => {
+      // eslint-disable-next-line no-console
+      console.error(err);
+      // eslint-disable-next-line no-alert
+      alert(intl.formatMessage(messages.advancedDetailsOLXEditFailed));
+    }).then(() => {
+      // Only if we succeeded:
+      setEditingOLX(false);
+    });
+  }, [editorRef, olxUpdater, intl]);
   return (
     <Collapsible
       styling="basic"
@@ -22,13 +48,37 @@ export const ComponentAdvancedInfo: React.FC<Props> = ({ usageKey }) => {
       <dl>
         <dt><FormattedMessage {...messages.advancedDetailsUsageKey} /></dt>
         <dd className="text-monospace small">{usageKey}</dd>
-        <dt>OLX Source</dt>
-        <dd>
-          {
-            olx ? <code className="micro">{olx}</code> : // eslint-disable-line
-            isOLXLoading ? <LoadingSpinner /> : // eslint-disable-line
-            <span>Error</span>
-          }
+        <dt><FormattedMessage {...messages.advancedDetailsOLX} /></dt>
+        <dd>{(() => {
+          if (isOLXLoading) { return <LoadingSpinner />; }
+          if (!olx) { return <FormattedMessage {...messages.advancedDetailsOLXError} />; }
+          return (
+            <>
+              <CodeEditor readOnly={!isEditingOLX} editorRef={editorRef}>{olx}</CodeEditor>
+              {
+                isEditingOLX
+                  ? (
+                    <>
+                      <Button variant="primary" onClick={updateOlx} disabled={olxUpdater.isLoading}>Save</Button>
+                      <Button variant="link" onClick={() => setEditingOLX(false)} disabled={olxUpdater.isLoading}>Cancel</Button>
+                    </>
+                  )
+                  : (
+                    <OverlayTrigger
+                      placement="bottom-start"
+                      overlay={(
+                        <Tooltip id="olx-edit-button">
+                          <FormattedMessage {...messages.advancedDetailsOLXEditWarning} />
+                        </Tooltip>
+                      )}
+                    >
+                      <Button variant="link" onClick={() => setEditingOLX(true)}><FormattedMessage {...messages.advancedDetailsOLXEditButton} /></Button>
+                    </OverlayTrigger>
+                  )
+                }
+            </>
+          );
+        })()}
         </dd>
       </dl>
     </Collapsible>
diff --git a/src/library-authoring/component-info/messages.ts b/src/library-authoring/component-info/messages.ts
index 0043639827..f7b00d2144 100644
--- a/src/library-authoring/component-info/messages.ts
+++ b/src/library-authoring/component-info/messages.ts
@@ -11,6 +11,26 @@ const messages = defineMessages({
     defaultMessage: 'OLX Source',
     description: 'Heading for the component\'s OLX source code',
   },
+  advancedDetailsOLXEditButton: {
+    id: 'course-authoring.library-authoring.component.advanced.olx-edit',
+    defaultMessage: 'Edit OLX',
+    description: 'Heading for the component\'s OLX source code',
+  },
+  advancedDetailsOLXEditWarning: {
+    id: 'course-authoring.library-authoring.component.advanced.olx-warning',
+    defaultMessage: 'Be careful! This is an advanced feature and errors may break the component.',
+    description: 'Warning for users about editing OLX directly.',
+  },
+  advancedDetailsOLXEditFailed: {
+    id: 'course-authoring.library-authoring.component.advanced.olx-failed',
+    defaultMessage: 'An error occurred and the OLX could not be saved.',
+    description: 'Error message shown when saving the OLX fails.',
+  },
+  advancedDetailsOLXError: {
+    id: 'course-authoring.library-authoring.component.advanced.olx-error',
+    defaultMessage: 'Unable to load OLX',
+    description: 'Error message if OLX is unavailable',
+  },
   advancedDetailsUsageKey: {
     id: 'course-authoring.library-authoring.component.advanced.usage-key',
     defaultMessage: 'ID (Usage key)',
diff --git a/src/library-authoring/data/api.ts b/src/library-authoring/data/api.ts
index 5c96176763..7d935eaa1f 100644
--- a/src/library-authoring/data/api.ts
+++ b/src/library-authoring/data/api.ts
@@ -318,6 +318,15 @@ export async function getXBlockOLX(usageKey: string): Promise<string> {
   return data.olx;
 }
 
+/**
+ * Set the OLX for the given XBlock.
+ * Returns the OLX as it was actually saved.
+ */
+export async function setXBlockOLX(usageKey: string, newOLX: string): Promise<string> {
+  const { data } = await getAuthenticatedHttpClient().post(getXBlockOLXApiUrl(usageKey), { olx: newOLX });
+  return data.olx;
+}
+
 /**
  * Get the collection metadata.
  */
diff --git a/src/library-authoring/data/apiHooks.ts b/src/library-authoring/data/apiHooks.ts
index 40601356b4..947da1c6da 100644
--- a/src/library-authoring/data/apiHooks.ts
+++ b/src/library-authoring/data/apiHooks.ts
@@ -31,6 +31,7 @@ import {
   updateCollectionComponents,
   type CreateLibraryCollectionDataRequest,
   getCollectionMetadata,
+  setXBlockOLX,
 } from './api';
 
 export const libraryQueryPredicate = (query: Query, libraryId: string): boolean => {
@@ -272,7 +273,7 @@ export const useCreateLibraryCollection = (libraryId: string) => {
   });
 };
 
-/* istanbul ignore next */ // This is only used in developer builds, and the associated UI doesn't work in test or prod
+/** Get the OLX source of a library component */
 export const useXBlockOLX = (usageKey: string) => (
   useQuery({
     queryKey: xblockQueryKeys.xblockOLX(usageKey),
@@ -281,6 +282,25 @@ export const useXBlockOLX = (usageKey: string) => (
   })
 );
 
+/**
+ * Update the OLX of a library component (advanced feature)
+ */
+export const useUpdateXBlockOLX = (usageKey: string) => {
+  const contentLibraryId = getLibraryId(usageKey);
+  const queryClient = useQueryClient();
+  return useMutation({
+    mutationFn: (newOLX: string) => setXBlockOLX(usageKey, newOLX),
+    onSuccess: (olxFromServer) => {
+      queryClient.setQueryData(xblockQueryKeys.xblockOLX(usageKey), olxFromServer);
+      // Reload the other data for this component:
+      invalidateComponentData(queryClient, contentLibraryId, usageKey);
+      // And the description and display name etc. may have changed, so refresh everything in the library too:
+      queryClient.invalidateQueries({ queryKey: libraryAuthoringQueryKeys.contentLibrary(contentLibraryId) });
+      queryClient.invalidateQueries({ predicate: (query) => libraryQueryPredicate(query, contentLibraryId) });
+    },
+  });
+};
+
 /**
  * Get the metadata for a collection in a library
  */