diff --git a/lldb/source/Plugins/SymbolFile/DWARF/DWARFUnit.h b/lldb/source/Plugins/SymbolFile/DWARF/DWARFUnit.h
--- a/lldb/source/Plugins/SymbolFile/DWARF/DWARFUnit.h
+++ b/lldb/source/Plugins/SymbolFile/DWARF/DWARFUnit.h
@@ -51,7 +51,7 @@
   uint64_t m_type_hash = 0;
   uint32_t m_type_offset = 0;
 
-  uint64_t m_dwo_id = 0;
+  llvm::Optional<uint64_t> m_dwo_id;
 
   DWARFUnitHeader() = default;
 
@@ -67,7 +67,7 @@
   }
   uint64_t GetTypeHash() const { return m_type_hash; }
   dw_offset_t GetTypeOffset() const { return m_type_offset; }
-  uint64_t GetDWOId() const { return m_dwo_id; }
+  llvm::Optional<uint64_t> GetDWOId() const { return m_dwo_id; }
   bool IsTypeUnit() const {
     return m_unit_type == llvm::dwarf::DW_UT_type ||
            m_unit_type == llvm::dwarf::DW_UT_split_type;
@@ -92,7 +92,7 @@
   virtual ~DWARFUnit();
 
   bool IsDWOUnit() { return m_is_dwo; }
-  uint64_t GetDWOId();
+  llvm::Optional<uint64_t> GetDWOId();
 
   void ExtractUnitDIEIfNeeded();
   void ExtractUnitDIENoDwoIfNeeded();
@@ -336,7 +336,7 @@
   bool m_is_dwo;
   bool m_has_parsed_non_skeleton_unit;
   /// Value of DW_AT_GNU_dwo_id (v4) or dwo_id from CU header (v5).
-  uint64_t m_dwo_id;
+  llvm::Optional<uint64_t> m_dwo_id;
 
 private:
   void ParseProducerInfo();
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/DWARFUnit.cpp b/lldb/source/Plugins/SymbolFile/DWARF/DWARFUnit.cpp
--- a/lldb/source/Plugins/SymbolFile/DWARF/DWARFUnit.cpp
+++ b/lldb/source/Plugins/SymbolFile/DWARF/DWARFUnit.cpp
@@ -77,12 +77,15 @@
 
   m_has_parsed_non_skeleton_unit = true;
 
+  if (!m_dwo_id)
+    return; // No DWO file.
+
   std::shared_ptr<SymbolFileDWARFDwo> dwo_symbol_file =
       m_dwarf.GetDwoSymbolFileForCompileUnit(*this, m_first_die);
   if (!dwo_symbol_file)
     return;
 
-  DWARFUnit *dwo_cu = dwo_symbol_file->GetDWOCompileUnitForHash(m_dwo_id);
+  DWARFUnit *dwo_cu = dwo_symbol_file->GetDWOCompileUnitForHash(*m_dwo_id);
 
   if (!dwo_cu)
     return; // Can't fetch the compile unit from the dwo file.
@@ -345,7 +348,7 @@
   SetStrOffsetsBase(baseOffset);
 }
 
-uint64_t DWARFUnit::GetDWOId() {
+llvm::Optional<uint64_t> DWARFUnit::GetDWOId() {
   ExtractUnitDIENoDwoIfNeeded();
   return m_dwo_id;
 }
@@ -467,7 +470,7 @@
       GetSymbolFileDWARF().GetObjectFile()->GetModule()->ReportError(
           "Failed to find location list contribution for CU with DWO Id "
           "0x%" PRIx64,
-          this->GetDWOId());
+          *GetDWOId());
       return;
     }
     offset += contribution->Offset;
@@ -889,8 +892,8 @@
         header.m_index_entry = Index->getFromHash(header.m_type_hash);
     } else {
       Index = &context.GetAsLLVM().getCUIndex();
-      if (*Index && header.m_version >= 5)
-        header.m_index_entry = Index->getFromHash(header.m_dwo_id);
+      if (*Index && header.m_version >= 5 && header.m_dwo_id)
+        header.m_index_entry = Index->getFromHash(*header.m_dwo_id);
     }
     if (!header.m_index_entry)
       header.m_index_entry = Index->getFromOffset(header.m_offset);
diff --git a/lldb/source/Plugins/SymbolFile/DWARF/ManualDWARFIndex.cpp b/lldb/source/Plugins/SymbolFile/DWARF/ManualDWARFIndex.cpp
--- a/lldb/source/Plugins/SymbolFile/DWARF/ManualDWARFIndex.cpp
+++ b/lldb/source/Plugins/SymbolFile/DWARF/ManualDWARFIndex.cpp
@@ -148,19 +148,36 @@
 
   const LanguageType cu_language = SymbolFileDWARF::GetLanguage(unit);
 
-  IndexUnitImpl(unit, cu_language, set);
-
-  if (SymbolFileDWARFDwo *dwo_symbol_file = unit.GetDwoSymbolFile()) {
-    // Type units in a dwp file are indexed separately, so we just need to
-    // process the split unit here. However, if the split unit is in a dwo file,
-    // then we need to process type units here.
-    if (dwo_symbol_file == dwp) {
-      IndexUnitImpl(unit.GetNonSkeletonUnit(), cu_language, set);
-    } else {
-      DWARFDebugInfo &dwo_info = dwo_symbol_file->DebugInfo();
-      for (size_t i = 0; i < dwo_info.GetNumUnits(); ++i)
-        IndexUnitImpl(*dwo_info.GetUnitAtIndex(i), cu_language, set);
+  // First check if the unit has a DWO ID. If it does then we only want to index
+  // the .dwo file or nothing at all. If we have a compile unit where we can't
+  // locate the .dwo/.dwp file we don't want to index anything from the skeleton
+  // compile unit because it is usally has no children unless
+  // -fsplit-dwarf-inlining was used at compile time. This option will add a
+  // copy of all DW_TAG_subprogram and any contained DW_TAG_inline_subroutine
+  // DIEs so that symbolication will still work in the absence of the .dwo/.dwp
+  // file, but the functions have no return types and all arguments and locals
+  // have been removed. So we don't want to index any of these hacked up
+  // function types. Types can still exist in the skeleton compile unit DWARF
+  // though as some functions have template parameter types and other things
+  // that cause extra copies of types to be included, but we should find these
+  // types in the .dwo file only as methods could have return types removed and
+  // we don't have to index incomplete types from the skeletone compile unit.
+  if (unit.GetDWOId()) {
+    if (SymbolFileDWARFDwo *dwo_symbol_file = unit.GetDwoSymbolFile()) {
+      // Type units in a dwp file are indexed separately, so we just need to
+      // process the split unit here. However, if the split unit is in a dwo file,
+      // then we need to process type units here.
+      if (dwo_symbol_file == dwp) {
+        IndexUnitImpl(unit.GetNonSkeletonUnit(), cu_language, set);
+      } else {
+        DWARFDebugInfo &dwo_info = dwo_symbol_file->DebugInfo();
+        for (size_t i = 0; i < dwo_info.GetNumUnits(); ++i)
+          IndexUnitImpl(*dwo_info.GetUnitAtIndex(i), cu_language, set);
+      }
     }
+  } else {
+    // We either have a normal compile unit which we want to index.
+    IndexUnitImpl(unit, cu_language, set);
   }
 }