diff --git a/lldb/source/Plugins/SymbolFile/PDB/PDBASTParser.cpp b/lldb/source/Plugins/SymbolFile/PDB/PDBASTParser.cpp
--- a/lldb/source/Plugins/SymbolFile/PDB/PDBASTParser.cpp
+++ b/lldb/source/Plugins/SymbolFile/PDB/PDBASTParser.cpp
@@ -1301,7 +1301,10 @@
         auto value = member->getValue();
         clang::QualType qual_type = decl->getType();
         unsigned type_width = m_ast.getASTContext().getIntWidth(qual_type);
-        unsigned constant_width = value.getBitWidth();
+        // If we have an incomplete type, the value may be empty, which will
+        // trigger an assertion failure on `getBitWidth`.
+        unsigned constant_width =
+            value.Type == llvm::pdb::Empty ? - 1 : value.getBitWidth();
 
         if (qual_type->isIntegralOrEnumerationType()) {
           if (type_width >= constant_width) {