diff --git a/llvm/lib/DebugInfo/DWARF/DWARFDebugLine.cpp b/llvm/lib/DebugInfo/DWARF/DWARFDebugLine.cpp
--- a/llvm/lib/DebugInfo/DWARF/DWARFDebugLine.cpp
+++ b/llvm/lib/DebugInfo/DWARF/DWARFDebugLine.cpp
@@ -340,18 +340,15 @@
   const uint64_t PrologueOffset = *OffsetPtr;
 
   clear();
-  TotalLength = DebugLineData.getRelocatedValue(4, OffsetPtr);
-  if (TotalLength == dwarf::DW_LENGTH_DWARF64) {
-    FormParams.Format = dwarf::DWARF64;
-    TotalLength = DebugLineData.getU64(OffsetPtr);
-  } else if (TotalLength >= dwarf::DW_LENGTH_lo_reserved) {
-    // Treat this error as unrecoverable - we have no way of knowing where the
-    // table ends.
-    return createStringError(errc::invalid_argument,
-        "parsing line table prologue at offset 0x%8.8" PRIx64
-        " unsupported reserved unit length found of value 0x%8.8" PRIx64,
-        PrologueOffset, TotalLength);
-  }
+  Error Err = Error::success();
+  std::tie(TotalLength, FormParams.Format) =
+      DebugLineData.getInitialLength(OffsetPtr, &Err);
+  if (Err)
+    return createStringError(
+        errc::invalid_argument,
+        "parsing line table prologue at offset 0x%8.8" PRIx64 ": %s",
+        PrologueOffset, toString(std::move(Err)).c_str());
+
   FormParams.Version = DebugLineData.getU16(OffsetPtr);
   if (!versionIsSupported(getVersion()))
     // Treat this error as unrecoverable - we cannot be sure what any of
@@ -360,7 +357,7 @@
     return createStringError(
         errc::not_supported,
         "parsing line table prologue at offset 0x%8.8" PRIx64
-        " found unsupported version %" PRIu16,
+        ": unsupported version %" PRIu16,
         PrologueOffset, getVersion());
 
   if (getVersion() >= 5) {
@@ -1218,8 +1215,7 @@
 }
 
 bool DWARFDebugLine::Prologue::totalLengthIsValid() const {
-  return TotalLength == dwarf::DW_LENGTH_DWARF64 ||
-         TotalLength < dwarf::DW_LENGTH_lo_reserved;
+  return TotalLength != 0u;
 }
 
 DWARFDebugLine::LineTable DWARFDebugLine::SectionParser::parseNext(
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
@@ -42,7 +42,7 @@
 ## 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 found of value 0xfffffffe
+# RESERVED: warning: parsing line table prologue at offset 0x00000048: unsupported reserved unit length of value 0xfffffffe
 # RESERVED-NOT: prologue
 # FATAL-NOT:  debug_line
 
@@ -50,7 +50,7 @@
 
 ## Version 0 table.
 # NONFATAL:      debug_line[0x00000048]
-# ALL:      warning: parsing line table prologue at offset 0x00000048 found unsupported version 0
+# ALL:      warning: parsing line table prologue at offset 0x00000048: unsupported version 0
 # NONFATAL-NEXT: Line table prologue
 # NONFATAL-NEXT:    total_length: 0x00000002
 # NONFATAL-NEXT:         version: 0
@@ -58,7 +58,7 @@
 
 ## Version 1 table.
 # NONFATAL:      debug_line[0x0000004e]
-# ALL-NEXT: warning: parsing line table prologue at offset 0x0000004e found unsupported version 1
+# ALL-NEXT: warning: parsing line table prologue at offset 0x0000004e: unsupported version 1
 # NONFATAL-NEXT: Line table prologue
 # NONFATAL-NEXT:    total_length: 0x00000002
 # NONFATAL-NEXT:         version: 1
diff --git a/llvm/unittests/DebugInfo/DWARF/DWARFDebugLineTest.cpp b/llvm/unittests/DebugInfo/DWARF/DWARFDebugLineTest.cpp
--- a/llvm/unittests/DebugInfo/DWARF/DWARFDebugLineTest.cpp
+++ b/llvm/unittests/DebugInfo/DWARF/DWARFDebugLineTest.cpp
@@ -316,8 +316,8 @@
   EXPECT_THAT_EXPECTED(
       getOrParseLineTableFatalErrors(),
       FailedWithMessage(
-          "parsing line table prologue at offset 0x00000000 unsupported "
-          "reserved unit length found of value 0xfffffff0"));
+          "parsing line table prologue at offset 0x00000000: unsupported "
+          "reserved unit length of value 0xfffffff0"));
 }
 
 struct DebugLineUnsupportedVersionFixture : public TestWithParam<uint16_t>,
@@ -339,8 +339,8 @@
 
   EXPECT_THAT_EXPECTED(
       getOrParseLineTableFatalErrors(),
-      FailedWithMessage("parsing line table prologue at offset 0x00000000 "
-                        "found unsupported version " +
+      FailedWithMessage("parsing line table prologue at offset 0x00000000: "
+                        "unsupported version " +
                         std::to_string(Version)));
 }
 
@@ -819,15 +819,15 @@
   DWARFDebugLine::SectionParser Parser(LineData, *Context, CUs, TUs);
   Parser.parseNext(RecordRecoverable, RecordUnrecoverable);
 
-  EXPECT_EQ(Parser.getOffset(), 4u);
+  EXPECT_EQ(Parser.getOffset(), 0u);
   EXPECT_TRUE(Parser.done());
   EXPECT_FALSE(Recoverable);
 
   EXPECT_THAT_ERROR(
       std::move(Unrecoverable),
       FailedWithMessage(
-          "parsing line table prologue at offset 0x00000000 unsupported "
-          "reserved unit length found of value 0xfffffff0"));
+          "parsing line table prologue at offset 0x00000000: unsupported "
+          "reserved unit length of value 0xfffffff0"));
 }
 
 TEST_F(DebugLineBasicFixture, ParserMovesToEndForBadLengthWhenSkipping) {
@@ -842,15 +842,15 @@
   DWARFDebugLine::SectionParser Parser(LineData, *Context, CUs, TUs);
   Parser.skip(RecordRecoverable, RecordUnrecoverable);
 
-  EXPECT_EQ(Parser.getOffset(), 4u);
+  EXPECT_EQ(Parser.getOffset(), 0u);
   EXPECT_TRUE(Parser.done());
   EXPECT_FALSE(Recoverable);
 
   EXPECT_THAT_ERROR(
       std::move(Unrecoverable),
       FailedWithMessage(
-          "parsing line table prologue at offset 0x00000000 unsupported "
-          "reserved unit length found of value 0xfffffff0"));
+          "parsing line table prologue at offset 0x00000000: unsupported "
+          "reserved unit length of value 0xfffffff0"));
 }
 
 TEST_F(DebugLineBasicFixture, ParserReportsFirstErrorInEachTableWhenParsing) {
@@ -873,10 +873,10 @@
 
   EXPECT_THAT_ERROR(
       std::move(Unrecoverable),
-      FailedWithMessage("parsing line table prologue at offset 0x00000000 "
-                        "found unsupported version 0",
-                        "parsing line table prologue at offset 0x00000006 "
-                        "found unsupported version 1"));
+      FailedWithMessage("parsing line table prologue at offset 0x00000000: "
+                        "unsupported version 0",
+                        "parsing line table prologue at offset 0x00000006: "
+                        "unsupported version 1"));
 }
 
 TEST_F(DebugLineBasicFixture, ParserReportsNonPrologueProblemsWhenParsing) {
@@ -932,10 +932,10 @@
 
   EXPECT_THAT_ERROR(
       std::move(Unrecoverable),
-      FailedWithMessage("parsing line table prologue at offset 0x00000000 "
-                        "found unsupported version 0",
-                        "parsing line table prologue at offset 0x00000006 "
-                        "found unsupported version 1"));
+      FailedWithMessage("parsing line table prologue at offset 0x00000000: "
+                        "unsupported version 0",
+                        "parsing line table prologue at offset 0x00000006: "
+                        "unsupported version 1"));
 }
 
 TEST_F(DebugLineBasicFixture, ParserIgnoresNonPrologueErrorsWhenSkipping) {