diff --git a/clang/lib/CodeGen/CGBuiltin.cpp b/clang/lib/CodeGen/CGBuiltin.cpp
index 50d34889d8dc1..40c6da27718bb 100644
--- a/clang/lib/CodeGen/CGBuiltin.cpp
+++ b/clang/lib/CodeGen/CGBuiltin.cpp
@@ -2836,6 +2836,10 @@ struct PaddingClearer {
     }
 
     for (auto *Field : R->fields()) {
+      // Treat unnamed bitfields as padding.
+      if (Field->isUnnamedBitField())
+        continue;
+
       auto FieldOffset = ASTLayout.getFieldOffset(Field->getFieldIndex());
       if (Field->isBitField()) {
         OccuppiedIntervals.push_back(BitInterval{
diff --git a/libcxx/test/libcxx/atomics/builtin_clear_padding.pass.cpp b/libcxx/test/libcxx/atomics/builtin_clear_padding.pass.cpp
index 32bcd376cdcf9..198686f4464c0 100644
--- a/libcxx/test/libcxx/atomics/builtin_clear_padding.pass.cpp
+++ b/libcxx/test/libcxx/atomics/builtin_clear_padding.pass.cpp
@@ -656,6 +656,26 @@ void structTests() {
     assert(memcmp(&s1, &s2, sizeof(S)) == 0);
   }
 
+  // unnamed bit fields
+  {
+    struct S {
+      unsigned int b1 : 1;
+      unsigned int    : 30;
+      unsigned int b2 : 1;
+    };
+
+    S s1, s2;
+    memset(&s1, 0, sizeof(S));
+    memset(&s2, 42, sizeof(S));
+
+    s1.b1 = 1;
+    s1.b2 = 1;
+    s2.b1 = 1;
+    s2.b2 = 1;
+    __builtin_clear_padding(&s2);
+    assert(memcmp(&s1, &s2, sizeof(S)) == 0);
+  }
+
   testAllStructsForType<32, 16, char>(11, 22, 33, 44);
   testAllStructsForType<64, 32, char>(4, 5, 6, 7);
   testAllStructsForType<32, 16, volatile char>(11, 22, 33, 44);