diff --git a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
--- a/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
+++ b/lldb/source/Plugins/SymbolFile/DWARF/SymbolFileDWARF.cpp
@@ -198,12 +198,17 @@
   return std::move(rel_path);
 }
 
-static FileSpecList ParseSupportFilesFromPrologue(
-    const lldb::ModuleSP &module,
-    const llvm::DWARFDebugLine::Prologue &prologue, FileSpec::Style style,
-    llvm::StringRef compile_dir = {}, FileSpec first_file = {}) {
+static FileSpecList
+ParseSupportFilesFromPrologue(const lldb::ModuleSP &module,
+                              const llvm::DWARFDebugLine::Prologue &prologue,
+                              FileSpec::Style style,
+                              llvm::StringRef compile_dir = {}) {
   FileSpecList support_files;
-  support_files.Append(first_file);
+  // File index 0 is not valid before DWARF v5. Add a dummy entry to ensure
+  // support file list indices match those we get from the debug info and line
+  // tables.
+  // TODO: Support DWARF v5.
+  support_files.Append(FileSpec());
 
   const size_t number_of_files = prologue.FileNames.size();
   for (size_t idx = 1; idx <= number_of_files; ++idx) {
@@ -1046,8 +1051,7 @@
 
   comp_unit.SetSupportFiles(ParseSupportFilesFromPrologue(
       comp_unit.GetModule(), line_table->Prologue, dwarf_cu->GetPathStyle(),
-      dwarf_cu->GetCompilationDirectory().GetCString(),
-      comp_unit.GetPrimaryFile()));
+      dwarf_cu->GetCompilationDirectory().GetCString()));
 
   return true;
 }
diff --git a/lldb/source/Plugins/SymbolFile/NativePDB/SymbolFileNativePDB.cpp b/lldb/source/Plugins/SymbolFile/NativePDB/SymbolFileNativePDB.cpp
--- a/lldb/source/Plugins/SymbolFile/NativePDB/SymbolFileNativePDB.cpp
+++ b/lldb/source/Plugins/SymbolFile/NativePDB/SymbolFileNativePDB.cpp
@@ -1110,9 +1110,7 @@
       // LLDB wants the index of the file in the list of support files.
       auto fn_iter = llvm::find(cci->m_file_list, *efn);
       lldbassert(fn_iter != cci->m_file_list.end());
-      // LLDB support file indices are 1-based.
-      uint32_t file_index =
-          1 + std::distance(cci->m_file_list.begin(), fn_iter);
+      uint32_t file_index = std::distance(cci->m_file_list.begin(), fn_iter);
 
       std::unique_ptr<LineSequence> sequence(
           line_table->CreateLineSequenceContainer());
@@ -1155,14 +1153,6 @@
     FileSpec spec(f, style);
     support_files.Append(spec);
   }
-
-  llvm::SmallString<64> main_source_file =
-      m_index->compilands().GetMainSourceFile(*cci);
-  FileSpec::Style style = main_source_file.startswith("/")
-                              ? FileSpec::Style::posix
-                              : FileSpec::Style::windows;
-  FileSpec spec(main_source_file, style);
-  support_files.Insert(0, spec);
   return true;
 }
 
diff --git a/lldb/source/Plugins/SymbolFile/PDB/SymbolFilePDB.cpp b/lldb/source/Plugins/SymbolFile/PDB/SymbolFilePDB.cpp
--- a/lldb/source/Plugins/SymbolFile/PDB/SymbolFilePDB.cpp
+++ b/lldb/source/Plugins/SymbolFile/PDB/SymbolFilePDB.cpp
@@ -371,10 +371,6 @@
     support_files.AppendIfUnique(spec);
   }
 
-  // LLDB uses the DWARF-like file numeration (one based),
-  // the zeroth file is the compile unit itself
-  support_files.Insert(0, comp_unit.GetPrimaryFile());
-
   return true;
 }
 
@@ -1881,9 +1877,7 @@
   if (!source_files)
     return;
 
-  // LLDB uses the DWARF-like file numeration (one based)
-  int index = 1;
-
+  int index = 0;
   while (auto file = source_files->getNext()) {
     uint32_t source_id = file->getUniqueId();
     index_map[source_id] = index++;
diff --git a/lldb/source/Symbol/CompileUnit.cpp b/lldb/source/Symbol/CompileUnit.cpp
--- a/lldb/source/Symbol/CompileUnit.cpp
+++ b/lldb/source/Symbol/CompileUnit.cpp
@@ -210,23 +210,12 @@
 uint32_t CompileUnit::FindLineEntry(uint32_t start_idx, uint32_t line,
                                     const FileSpec *file_spec_ptr, bool exact,
                                     LineEntry *line_entry_ptr) {
-  uint32_t file_idx = 0;
+  if (!file_spec_ptr)
+    file_spec_ptr = &GetPrimaryFile();
+  uint32_t file_idx = GetSupportFiles().FindFileIndex(0, *file_spec_ptr, true);
+  if (file_idx == UINT32_MAX)
+    return UINT32_MAX;
 
-  if (file_spec_ptr) {
-    file_idx = GetSupportFiles().FindFileIndex(1, *file_spec_ptr, true);
-    if (file_idx == UINT32_MAX)
-      return UINT32_MAX;
-  } else {
-    // All the line table entries actually point to the version of the Compile
-    // Unit that is in the support files (the one at 0 was artificially added.)
-    // So prefer the one further on in the support files if it exists...
-    const FileSpecList &support_files = GetSupportFiles();
-    const bool full = true;
-    file_idx = support_files.FindFileIndex(
-        1, support_files.GetFileSpecAtIndex(0), full);
-    if (file_idx == UINT32_MAX)
-      file_idx = 0;
-  }
   LineTable *line_table = GetLineTable();
   if (line_table)
     return line_table->FindLineEntryIndexByFileIndex(start_idx, file_idx, line,
@@ -253,7 +242,7 @@
     return;
 
   uint32_t file_idx =
-      GetSupportFiles().FindFileIndex(1, file_spec, true);
+      GetSupportFiles().FindFileIndex(0, file_spec, true);
   while (file_idx != UINT32_MAX) {
     file_indexes.push_back(file_idx);
     file_idx = GetSupportFiles().FindFileIndex(file_idx + 1, file_spec, true);