Index: llvm/test/tools/llvm-objdump/ELF/ARM/debug-vars-dwarf4.s
===================================================================
--- llvm/test/tools/llvm-objdump/ELF/ARM/debug-vars-dwarf4.s
+++ llvm/test/tools/llvm-objdump/ELF/ARM/debug-vars-dwarf4.s
@@ -45,6 +45,9 @@
 # RUN: llvm-mc -triple armv8a--none-eabi < %s -filetype=obj | \
 # RUN:     llvm-objdump - -d --debug-vars=ascii | \
 # RUN:     FileCheck %s --check-prefix=ASCII --strict-whitespace
+# RUN: llvm-mc -triple armv8a--none-eabi < %s -filetype=obj | \
+# RUN:     not llvm-objdump - -d --debug-vars=bad_value 2>&1 | \
+# RUN:     FileCheck %s --check-prefix=ERROR
 
 ## Note that llvm-objdump emits tab characters in the disassembly, assuming an
 ## 8-byte tab stop, so these might not look aligned in a text editor.
@@ -146,6 +149,8 @@
 # ASCII-NEXT:        c: 01 00 80 e2  	add	r0, r0, #1                                  |         
 # ASCII-NEXT:       10: 1e ff 2f e1  	bx	lr                                          v         
 
+# ERROR: error: 'bad_value' is not a valid value for '--debug-vars='
+
 	.text
 	.syntax unified
 	.eabi_attribute	67, "2.09"
Index: llvm/test/tools/llvm-objdump/dwarf_invalid.yaml
===================================================================
--- /dev/null
+++ llvm/test/tools/llvm-objdump/dwarf_invalid.yaml
@@ -0,0 +1,12 @@
+## Test invalid use of the --dwarf option
+
+# RUN: yaml2obj %s -o %t
+# RUN: not llvm-objdump --dwarf=bad_value %t 2>&1 | FileCheck %s --check-prefix=ERROR
+
+# ERROR: error: 'bad_value' is not a valid value for '--dwarf='
+
+--- !ELF
+FileHeader:
+  Class:   ELFCLASS64
+  Data:    ELFDATA2LSB
+  Type:    ET_REL
Index: llvm/tools/llvm-objdump/llvm-objdump.h
===================================================================
--- llvm/tools/llvm-objdump/llvm-objdump.h
+++ llvm/tools/llvm-objdump/llvm-objdump.h
@@ -31,11 +31,7 @@
 
 namespace objdump {
 
-enum DebugVarsFormat {
-  DVDisabled,
-  DVUnicode,
-  DVASCII,
-};
+enum DebugVarsFormat { DVDisabled, DVUnicode, DVASCII, DVInvalid };
 
 extern bool ArchiveHeaders;
 extern int DbgIndent;
Index: llvm/tools/llvm-objdump/llvm-objdump.cpp
===================================================================
--- llvm/tools/llvm-objdump/llvm-objdump.cpp
+++ llvm/tools/llvm-objdump/llvm-objdump.cpp
@@ -2500,6 +2500,11 @@
   }
 }
 
+static void invalidArgValue(const opt::Arg *A) {
+  reportCmdLineError("'" + StringRef(A->getValue()) +
+                     "' is not a valid value for '" + A->getSpelling() + "'");
+}
+
 static std::vector<std::string>
 commaSeparatedValues(const llvm::opt::InputArgList &InputArgs, int ID) {
   std::vector<std::string> Values;
@@ -2573,8 +2578,11 @@
       commaSeparatedValues(InputArgs, OBJDUMP_disassemble_symbols_EQ);
   DisassembleZeroes = InputArgs.hasArg(OBJDUMP_disassemble_zeroes);
   if (const opt::Arg *A = InputArgs.getLastArg(OBJDUMP_dwarf_EQ)) {
-    DwarfDumpType =
-        StringSwitch<DIDumpType>(A->getValue()).Case("frames", DIDT_DebugFrame);
+    DwarfDumpType = StringSwitch<DIDumpType>(A->getValue())
+                        .Case("frames", DIDT_DebugFrame)
+                        .Default(DIDT_Null);
+    if (DwarfDumpType == DIDT_Null)
+      invalidArgValue(A);
   }
   DynamicRelocations = InputArgs.hasArg(OBJDUMP_dynamic_reloc);
   FaultMapSection = InputArgs.hasArg(OBJDUMP_fault_map_section);
@@ -2611,7 +2619,10 @@
   if (const opt::Arg *A = InputArgs.getLastArg(OBJDUMP_debug_vars_EQ)) {
     DbgVariables = StringSwitch<DebugVarsFormat>(A->getValue())
                        .Case("ascii", DVASCII)
-                       .Case("unicode", DVUnicode);
+                       .Case("unicode", DVUnicode)
+                       .Default(DVInvalid);
+    if (DbgVariables == DVInvalid)
+      invalidArgValue(A);
   }
   parseIntArg(InputArgs, OBJDUMP_debug_vars_indent_EQ, DbgIndent);