diff --git a/lucene/CHANGES.txt b/lucene/CHANGES.txt
index 6dbd8fb2f28..91672abe220 100644
--- a/lucene/CHANGES.txt
+++ b/lucene/CHANGES.txt
@@ -219,6 +219,9 @@ Bug Fixes
   that rewrites to a MatchNoDocsQuery instead of throwing an exception.
   (Bjarke Mortensen, Andy Tran via David Smiley)
 
+* LUCENE-8287: Ensure that empty regex completion queries always return no results.
+  (Julie Tibshirani via Jim Ferenczi)
+
 Other
 
 * LUCENE-8301: Update randomizedtesting to 2.6.0. (Dawid Weiss)
diff --git a/lucene/suggest/src/java/org/apache/lucene/search/suggest/document/ContextQuery.java b/lucene/suggest/src/java/org/apache/lucene/search/suggest/document/ContextQuery.java
index 467708a2728..6217ca38f85 100644
--- a/lucene/suggest/src/java/org/apache/lucene/search/suggest/document/ContextQuery.java
+++ b/lucene/suggest/src/java/org/apache/lucene/search/suggest/document/ContextQuery.java
@@ -167,11 +167,19 @@ public class ContextQuery extends CompletionQuery {
   @Override
   public Weight createWeight(IndexSearcher searcher, ScoreMode scoreMode, float boost) throws IOException {
     final CompletionWeight innerWeight = ((CompletionWeight) innerQuery.createWeight(searcher, scoreMode, boost));
+    final Automaton innerAutomaton = innerWeight.getAutomaton();
+
+    // If the inner automaton matches nothing, then we return an empty weight to avoid
+    // traversing all contexts during scoring.
+    if (innerAutomaton.getNumStates() == 0) {
+      return new CompletionWeight(this, innerAutomaton);
+    }
+
     // if separators are preserved the fst contains a SEP_LABEL
     // behind each gap. To have a matching automaton, we need to
     // include the SEP_LABEL in the query as well
     Automaton optionalSepLabel = Operations.optional(Automata.makeChar(CompletionAnalyzer.SEP_LABEL));
-    Automaton prefixAutomaton = Operations.concatenate(optionalSepLabel, innerWeight.getAutomaton());
+    Automaton prefixAutomaton = Operations.concatenate(optionalSepLabel, innerAutomaton);
     Automaton contextsAutomaton = Operations.concatenate(toContextAutomaton(contexts, matchAllContexts), prefixAutomaton);
     contextsAutomaton = Operations.determinize(contextsAutomaton, Operations.DEFAULT_MAX_DETERMINIZED_STATES);
 
diff --git a/lucene/suggest/src/java/org/apache/lucene/search/suggest/document/RegexCompletionQuery.java b/lucene/suggest/src/java/org/apache/lucene/search/suggest/document/RegexCompletionQuery.java
index b53ac34bef4..6fa547a7f60 100644
--- a/lucene/suggest/src/java/org/apache/lucene/search/suggest/document/RegexCompletionQuery.java
+++ b/lucene/suggest/src/java/org/apache/lucene/search/suggest/document/RegexCompletionQuery.java
@@ -23,6 +23,8 @@ import org.apache.lucene.search.IndexSearcher;
 import org.apache.lucene.search.ScoreMode;
 import org.apache.lucene.search.Weight;
 import org.apache.lucene.search.suggest.BitsProducer;
+import org.apache.lucene.util.automaton.Automata;
+import org.apache.lucene.util.automaton.Automaton;
 import org.apache.lucene.util.automaton.Operations;
 import org.apache.lucene.util.automaton.RegExp;
 
@@ -90,7 +92,12 @@ public class RegexCompletionQuery extends CompletionQuery {
 
   @Override
   public Weight createWeight(IndexSearcher searcher, ScoreMode scoreMode, float boost) throws IOException {
-    return new CompletionWeight(this, new RegExp(getTerm().text(), flags).toAutomaton(maxDeterminizedStates));
+    // If an empty regex is provided, we return an automaton that matches nothing. This ensures
+    // consistency with PrefixCompletionQuery, which returns no results for an empty term.
+    Automaton automaton = getTerm().text().isEmpty()
+        ? Automata.makeEmpty()
+        : new RegExp(getTerm().text(), flags).toAutomaton(maxDeterminizedStates);
+    return new CompletionWeight(this, automaton);
   }
 
   /**
diff --git a/lucene/suggest/src/test/org/apache/lucene/search/suggest/document/TestPrefixCompletionQuery.java b/lucene/suggest/src/test/org/apache/lucene/search/suggest/document/TestPrefixCompletionQuery.java
index 515ac2db32e..5e941dd4e2d 100644
--- a/lucene/suggest/src/test/org/apache/lucene/search/suggest/document/TestPrefixCompletionQuery.java
+++ b/lucene/suggest/src/test/org/apache/lucene/search/suggest/document/TestPrefixCompletionQuery.java
@@ -41,6 +41,7 @@ import org.apache.lucene.util.FixedBitSet;
 import org.apache.lucene.util.LuceneTestCase;
 import org.junit.After;
 import org.junit.Before;
+import org.junit.Test;
 
 import static org.apache.lucene.search.DocIdSetIterator.NO_MORE_DOCS;
 import static org.apache.lucene.search.suggest.document.TestSuggestField.Entry;
@@ -142,6 +143,29 @@ public class TestPrefixCompletionQuery extends LuceneTestCase {
     iw.close();
   }
 
+  @Test
+  public void testEmptyPrefixQuery() throws Exception {
+    Analyzer analyzer = new MockAnalyzer(random());
+    RandomIndexWriter iw = new RandomIndexWriter(random(), dir, iwcWithSuggestField(analyzer, "suggest_field"));
+    Document document = new Document();
+    document.add(new SuggestField("suggest_field", "suggestion1", 1));
+    iw.addDocument(document);
+
+    if (rarely()) {
+      iw.commit();
+    }
+
+    DirectoryReader reader = iw.getReader();
+    SuggestIndexSearcher suggestIndexSearcher = new SuggestIndexSearcher(reader);
+    PrefixCompletionQuery query = new PrefixCompletionQuery(analyzer, new Term("suggest_field", ""));
+
+    TopSuggestDocs suggest = suggestIndexSearcher.suggest(query, 5, false);
+    assertEquals(0, suggest.scoreDocs.length);
+
+    reader.close();
+    iw.close();
+  }
+
   public void testMostlyFilteredOutDocuments() throws Exception {
     Analyzer analyzer = new MockAnalyzer(random());
     RandomIndexWriter iw = new RandomIndexWriter(random(), dir, iwcWithSuggestField(analyzer, "suggest_field"));
@@ -337,4 +361,27 @@ public class TestPrefixCompletionQuery extends LuceneTestCase {
     reader.close();
     iw.close();
   }
+
+  public void testEmptyPrefixContextQuery() throws Exception {
+    Analyzer analyzer = new MockAnalyzer(random());
+    RandomIndexWriter iw = new RandomIndexWriter(random(), dir, iwcWithSuggestField(analyzer, "suggest_field"));
+    Document document = new Document();
+    document.add(new ContextSuggestField("suggest_field", "suggestion", 1, "type"));
+    iw.addDocument(document);
+
+    if (rarely()) {
+      iw.commit();
+    }
+
+    DirectoryReader reader = iw.getReader();
+    SuggestIndexSearcher suggestIndexSearcher = new SuggestIndexSearcher(reader);
+    ContextQuery query = new ContextQuery(new PrefixCompletionQuery(analyzer, new Term("suggest_field", "")));
+    query.addContext("type", 1);
+
+    TopSuggestDocs suggest = suggestIndexSearcher.suggest(query, 5, false);
+    assertEquals(0, suggest.scoreDocs.length);
+
+    reader.close();
+    iw.close();
+  }
 }
diff --git a/lucene/suggest/src/test/org/apache/lucene/search/suggest/document/TestRegexCompletionQuery.java b/lucene/suggest/src/test/org/apache/lucene/search/suggest/document/TestRegexCompletionQuery.java
index 2dd718407fd..7684bb071bd 100644
--- a/lucene/suggest/src/test/org/apache/lucene/search/suggest/document/TestRegexCompletionQuery.java
+++ b/lucene/suggest/src/test/org/apache/lucene/search/suggest/document/TestRegexCompletionQuery.java
@@ -75,6 +75,29 @@ public class TestRegexCompletionQuery extends LuceneTestCase {
     iw.close();
   }
 
+  @Test
+  public void testEmptyRegexQuery() throws Exception {
+    Analyzer analyzer = new MockAnalyzer(random());
+    RandomIndexWriter iw = new RandomIndexWriter(random(), dir, iwcWithSuggestField(analyzer, "suggest_field"));
+    Document document = new Document();
+    document.add(new SuggestField("suggest_field", "suggestion1", 1));
+    iw.addDocument(document);
+
+    if (rarely()) {
+      iw.commit();
+    }
+
+    DirectoryReader reader = iw.getReader();
+    SuggestIndexSearcher suggestIndexSearcher = new SuggestIndexSearcher(reader);
+    RegexCompletionQuery query = new RegexCompletionQuery(new Term("suggest_field", ""));
+
+    TopSuggestDocs suggest = suggestIndexSearcher.suggest(query, 5, false);
+    assertEquals(0, suggest.scoreDocs.length);
+
+    reader.close();
+    iw.close();
+  }
+
   @Test
   public void testSimpleRegexContextQuery() throws Exception {
     Analyzer analyzer = new MockAnalyzer(random());
@@ -147,4 +170,28 @@ public class TestRegexCompletionQuery extends LuceneTestCase {
     reader.close();
     iw.close();
   }
+
+  @Test
+  public void testEmptyRegexContextQuery() throws Exception {
+    Analyzer analyzer = new MockAnalyzer(random());
+    RandomIndexWriter iw = new RandomIndexWriter(random(), dir, iwcWithSuggestField(analyzer, "suggest_field"));
+    Document document = new Document();
+    document.add(new ContextSuggestField("suggest_field", "suggestion", 1, "type"));
+    iw.addDocument(document);
+
+    if (rarely()) {
+      iw.commit();
+    }
+
+    DirectoryReader reader = iw.getReader();
+    SuggestIndexSearcher suggestIndexSearcher = new SuggestIndexSearcher(reader);
+    ContextQuery query = new ContextQuery(new RegexCompletionQuery(new Term("suggest_field", "")));
+    query.addContext("type", 1);
+
+    TopSuggestDocs suggest = suggestIndexSearcher.suggest(query, 5, false);
+    assertEquals(0, suggest.scoreDocs.length);
+
+    reader.close();
+    iw.close();
+  }
 }