diff --git a/llvm/lib/DebugInfo/DWARF/DWARFContext.cpp b/llvm/lib/DebugInfo/DWARF/DWARFContext.cpp
--- a/llvm/lib/DebugInfo/DWARF/DWARFContext.cpp
+++ b/llvm/lib/DebugInfo/DWARF/DWARFContext.cpp
@@ -491,6 +491,9 @@
   auto DumpLineSection = [&](DWARFDebugLine::SectionParser Parser,
                              DIDumpOptions DumpOpts,
                              Optional<uint64_t> DumpOffset) {
+    // Flush immediately to ensure error messages from parsing are printed after
+    // any existing output.
+    OS.flush();
     while (!Parser.done()) {
       if (DumpOffset && Parser.getOffset() != *DumpOffset) {
         Parser.skip(DumpOpts.WarningHandler, DumpOpts.WarningHandler);
@@ -498,6 +501,8 @@
       }
       OS << "debug_line[" << format("0x%8.8" PRIx64, Parser.getOffset())
          << "]\n";
+      // Flush after the table header is printed to ensure error messages for
+      // this table are printed after it.
       OS.flush();
       if (DumpOpts.Verbose) {
         Parser.parseNext(DumpOpts.WarningHandler, DumpOpts.WarningHandler, &OS);
@@ -506,6 +511,8 @@
             Parser.parseNext(DumpOpts.WarningHandler, DumpOpts.WarningHandler);
         LineTable.dump(OS, DumpOpts);
       }
+      // Flush now to ensure later error output does not get mixed in with the
+      // line table output.
       OS.flush();
     }
   };
diff --git a/llvm/test/tools/llvm-dwarfdump/X86/debug_line_invalid.test b/llvm/test/tools/llvm-dwarfdump/X86/debug_line_invalid.test
--- a/llvm/test/tools/llvm-dwarfdump/X86/debug_line_invalid.test
+++ b/llvm/test/tools/llvm-dwarfdump/X86/debug_line_invalid.test
@@ -4,40 +4,43 @@
 ## Show that a bad length stops parsing of the section.
 # RUN: llvm-mc -triple x86_64-pc-linux %S/Inputs/debug_line_reserved_length.s -filetype=obj -o %t-reserved.o
 # RUN: llvm-dwarfdump -debug-line %t-reserved.o 2>&1 \
-# RUN:   | FileCheck %s --check-prefixes=FIRST,FATAL,RESERVED
+# RUN:   | FileCheck %s --check-prefixes=HEADER,FIRST,FATAL,RESERVED
 # RUN: llvm-dwarfdump -debug-line %t-reserved.o -verbose 2>&1 \
-# RUN:   | FileCheck %s --check-prefixes=FIRST,FATAL,RESERVED
+# RUN:   | FileCheck %s --check-prefixes=HEADER,FIRST,FATAL,RESERVED
 
 ## We only produce warnings for malformed tables after the specified unit if
 ## parsing can continue.
 # RUN: llvm-dwarfdump -debug-line=0 %t-reserved.o 2>&1 \
-# RUN:   | FileCheck %s --check-prefixes=FIRST,NOLATER,RESERVED
+# RUN:   | FileCheck %s --check-prefixes=HEADER,FIRST,NOLATER,RESERVED
 
 ## Stop looking for the specified unit, if a fatally-bad prologue is detected.
 # RUN: llvm-dwarfdump -debug-line=0x4b %t-reserved.o 2>&1 \
-# RUN:   | FileCheck %s --check-prefixes=NOFIRST,NOLATER,RESERVED
+# RUN:   | FileCheck %s --check-prefixes=HEADER,NOFIRST,NOLATER,RESERVED
 
 ## Show that non-fatal errors do not prevent parsing the rest of the section.
 # RUN: llvm-mc -triple x86_64-pc-linux %S/Inputs/debug_line_malformed.s -filetype=obj -o %t-malformed.o
 # RUN: llvm-dwarfdump -debug-line %t-malformed.o 2> %t-malformed.err \
-# RUN:   | FileCheck %s --check-prefixes=FIRST,NONFATAL,LAST --implicit-check-not='debug_line[{{.*}}]'
+# RUN:   | FileCheck %s --check-prefixes=HEADER,FIRST,NONFATAL,LAST --implicit-check-not='debug_line[{{.*}}]'
 # RUN: FileCheck %s --input-file=%t-malformed.err --check-prefixes=ALL,OTHER
 # RUN: llvm-dwarfdump -debug-line %t-malformed.o -verbose 2> %t-malformed-verbose.err \
-# RUN:   | FileCheck %s --check-prefixes=FIRST,NONFATAL,LAST --implicit-check-not='debug_line[{{.*}}]'
+# RUN:   | FileCheck %s --check-prefixes=HEADER,FIRST,NONFATAL,LAST --implicit-check-not='debug_line[{{.*}}]'
 # RUN: FileCheck %s --input-file=%t-malformed-verbose.err --check-prefixes=ALL,OTHER
 
 ## We should still produce warnings for malformed tables after the specified unit.
 # RUN: llvm-dwarfdump -debug-line=0 %t-malformed.o 2> %t-malformed-off-first.err \
-# RUN:   | FileCheck %s --check-prefixes=FIRST,NOLATER
+# RUN:   | FileCheck %s --check-prefixes=HEADER,FIRST,NOLATER
 # RUN: FileCheck %s --input-file=%t-malformed-off-first.err --check-prefix=ALL
 
 ## Don't stop looking for the later unit if non-fatal issues are found.
 # RUN: llvm-dwarfdump -debug-line=0x3c9 %t-malformed.o 2> %t-malformed-off-last.err \
-# RUN:   | FileCheck %s --check-prefix=LAST --implicit-check-not='debug_line[{{.*}}]'
+# RUN:   | FileCheck %s --check-prefixes=HEADER,LAST --implicit-check-not='debug_line[{{.*}}]'
 # RUN: FileCheck %s --input-file=%t-malformed-off-last.err --check-prefix=ALL
 
+# HEADER:      .debug_line contents:
+
 # FIRST:       debug_line[0x00000000]
 # FIRST:       0x000000000badbeef {{.*}} end_sequence
+# FIRST-EMPTY:
 # NOFIRST-NOT: debug_line[0x00000000]
 # NOFIRST-NOT: 0x000000000badbeef {{.*}} end_sequence
 # NOLATER-NOT: debug_line[{{.*}}]
@@ -45,8 +48,7 @@
 
 ## For fatal issues, the following table(s) should not be dumped:
 # FATAL:      debug_line[0x00000048]
-# RESERVED-NOT: prologue
-# RESERVED: warning: parsing line table prologue at offset 0x00000048: unsupported reserved unit length of value 0xfffffffe
+# RESERVED-NEXT: warning: parsing line table prologue at offset 0x00000048: unsupported reserved unit length of value 0xfffffffe
 # RESERVED-NOT: prologue
 # FATAL-NOT:  debug_line