Index: llvm/lib/DebugInfo/DWARF/DWARFDebugFrame.cpp
===================================================================
--- llvm/lib/DebugInfo/DWARF/DWARFDebugFrame.cpp
+++ llvm/lib/DebugInfo/DWARF/DWARFDebugFrame.cpp
@@ -285,6 +285,18 @@
   }
 }
 
+// Returns the CIE identifier to be used by the requested format.
+// CIE ids for .debug_frame sections are defined in Section 7.24 of DWARFv5.
+// For CIE ID in .eh_frame sections see
+// https://refspecs.linuxfoundation.org/LSB_5.0.0/LSB-Core-generic/LSB-Core-generic/ehframechpt.html
+constexpr uint64_t getCIEId(bool IsDWARF64, bool IsEH) {
+  if (IsEH)
+    return 0;
+  if (IsDWARF64)
+    return DW64_CIE_ID;
+  return DW_CIE_ID;
+}
+
 void CIE::dump(raw_ostream &OS, const MCRegisterInfo *MRI, bool IsEH) const {
   OS << format("%08x %08x %08x CIE", (uint32_t)Offset, (uint32_t)Length,
                IsEH ? 0 : DW_CIE_ID)
@@ -385,10 +397,7 @@
 
     // The Id field's size depends on the DWARF format
     Id = Data.getRelocatedValue((IsDWARF64 && !IsEH) ? 8 : 4, &Offset);
-    bool IsCIE =
-        ((IsDWARF64 && Id == DW64_CIE_ID) || Id == DW_CIE_ID || (IsEH && !Id));
-
-    if (IsCIE) {
+    if (Id == getCIEId(IsDWARF64, IsEH)) {
       uint8_t Version = Data.getU8(&Offset);
       const char *Augmentation = Data.getCStr(&Offset);
       StringRef AugmentationString(Augmentation ? Augmentation : "");
Index: llvm/test/DebugInfo/X86/debug-frame-cie-id-dwarf64.s
===================================================================
--- /dev/null
+++ llvm/test/DebugInfo/X86/debug-frame-cie-id-dwarf64.s
@@ -0,0 +1,16 @@
+# RUN: llvm-mc -triple x86_64-unknown-linux %s -filetype=obj -o - | \
+# RUN:   llvm-dwarfdump -debug-frame - | \
+# RUN:   FileCheck %s
+
+# CHECK: 00000000 {{.*}} FDE
+
+        .section .debug_frame,"",@progbits
+## This FDE was formerly wrongly interpreted as a CIE because its CIE pointer
+## is similar to DWARF32 CIE id.
+        .long 0xffffffff        # DWARF64 mark
+        .quad .Lend - .LCIEptr  # Length
+.LCIEptr:
+        .quad 0xffffffff        # CIE pointer
+        .quad 0x1111abcd        # Initial location
+        .quad 0x00010000        # Address range
+.Lend:
Index: llvm/test/DebugInfo/X86/eh-frame-cie-id.s
===================================================================
--- /dev/null
+++ llvm/test/DebugInfo/X86/eh-frame-cie-id.s
@@ -0,0 +1,15 @@
+# RUN: llvm-mc -triple x86_64-unknown-linux %s -filetype=obj -o - | \
+# RUN:   not --crash llvm-dwarfdump -debug-frame - 2>&1 | \
+# RUN:   FileCheck %s
+
+# CHECK: Parsing FDE data at 0 failed due to missing CIE
+
+        .section .eh_frame,"a",@unwind
+## This FDE was formerly wrongly interpreted as a CIE because its CIE pointer
+## is similar to CIE id of a .debug_frame FDE.
+        .long .Lend - .LCIEptr  # Length
+.LCIEptr:
+        .long 0xffffffff        # CIE pointer
+        .quad 0x1111abcd        # Initial location
+        .quad 0x00010000        # Address range
+.Lend: