Index: docs/CommandGuide/llvm-symbolizer.rst
===================================================================
--- docs/CommandGuide/llvm-symbolizer.rst
+++ docs/CommandGuide/llvm-symbolizer.rst
@@ -72,7 +72,7 @@
 
   Path to object file to be symbolized.
 
-.. option:: -functions=[none|short|linkage]
+.. option:: -functions[=<none|short|linkage>], -f
 
   Specify the way function names are printed (omit function name,
   print short function name, or print full linkage name, respectively).
Index: test/DebugInfo/llvm-symbolizer.test
===================================================================
--- test/DebugInfo/llvm-symbolizer.test
+++ test/DebugInfo/llvm-symbolizer.test
@@ -207,23 +207,22 @@
 
 STRIPPED:  global_func
 
-RUN: echo "%p/Inputs/dwarfdump-test4.elf-x86-64 0x62c" > %t.input7
-RUN: llvm-symbolizer --functions=short --demangle=false < %t.input7 \
-RUN:    | FileCheck %s --check-prefix=SHORT_FUNCTION_NAME
-RUN: llvm-symbolizer --functions=short -C=false < %t.input7 \
-RUN:    | FileCheck %s --check-prefix=SHORT_FUNCTION_NAME
-
-SHORT_FUNCTION_NAME-NOT: _Z1cv
-
 ; Check that the last of --demangle and --no-demangle wins.
+RUN: echo "%p/Inputs/dwarfdump-test4.elf-x86-64 0x62c" > %t.input7
 RUN: llvm-symbolizer --demangle < %t.input7 \
 RUN:    | FileCheck %s --check-prefix=DEMANGLED_FUNCTION_NAME
+RUN: llvm-symbolizer -C < %t.input7 \
+RUN:    | FileCheck %s --check-prefix=DEMANGLED_FUNCTION_NAME
 RUN: llvm-symbolizer --no-demangle < %t.input7 \
 RUN:    | FileCheck %s --check-prefix=MANGLED_FUNCTION_NAME
 RUN: llvm-symbolizer --demangle --no-demangle < %t.input7 \
 RUN:    | FileCheck %s --check-prefix=MANGLED_FUNCTION_NAME
+RUN: llvm-symbolizer -C --no-demangle < %t.input7 \
+RUN:    | FileCheck %s --check-prefix=MANGLED_FUNCTION_NAME
 RUN: llvm-symbolizer --no-demangle --demangle < %t.input7 \
 RUN:    | FileCheck %s --check-prefix=DEMANGLED_FUNCTION_NAME
+RUN: llvm-symbolizer --no-demangle -C < %t.input7 \
+RUN:    | FileCheck %s --check-prefix=DEMANGLED_FUNCTION_NAME
 
 MANGLED_FUNCTION_NAME: _Z1cv
 DEMANGLED_FUNCTION_NAME: c()
Index: test/tools/llvm-symbolizer/Inputs/functions.cpp
===================================================================
--- test/tools/llvm-symbolizer/Inputs/functions.cpp
+++ test/tools/llvm-symbolizer/Inputs/functions.cpp
@@ -0,0 +1,2 @@
+// Build using clang -target x86_64-pc-linux -c -g
+void foo(int bar) {}
Index: test/tools/llvm-symbolizer/functions.test
===================================================================
--- test/tools/llvm-symbolizer/functions.test
+++ test/tools/llvm-symbolizer/functions.test
@@ -0,0 +1,22 @@
+# REQUIRES: x86-registered-target
+
+# RUN: llvm-symbolizer 0 --obj=%p/Inputs/functions.o | FileCheck %s --check-prefix=LINKAGE
+# RUN: llvm-symbolizer 0 --functions --obj=%p/Inputs/functions.o | FileCheck %s --check-prefix=LINKAGE
+# RUN: llvm-symbolizer 0 --functions=linkage --obj=%p/Inputs/functions.o | FileCheck %s --check-prefix=LINKAGE
+# RUN: llvm-symbolizer 0 --functions=short --obj=%p/Inputs/functions.o | FileCheck %s --check-prefix=SHORT
+# RUN: llvm-symbolizer 0 --functions=none --obj=%p/Inputs/functions.o | FileCheck %s --check-prefix=NONE
+
+## Characterise behaviour for no '=' sign. llvm-symbolizer treats the next option as an
+## input address, and just prints it.
+# RUN: llvm-symbolizer 0 --functions none --obj=%p/Inputs/functions.o | FileCheck %s --check-prefixes=LINKAGE,ERR
+
+# LINKAGE:      {{^}}foo(int){{$}}
+# LINKAGE-NEXT: functions.cpp:2:0
+
+# SHORT:      {{^}}foo{{$}}
+# SHORT-NEXT: functions.cpp:2:0
+
+# NONE-NOT: foo
+# NONE:     functions.cpp:2:0
+
+# ERR: none
Index: tools/llvm-symbolizer/llvm-symbolizer.cpp
===================================================================
--- tools/llvm-symbolizer/llvm-symbolizer.cpp
+++ tools/llvm-symbolizer/llvm-symbolizer.cpp
@@ -38,12 +38,17 @@
 
 static cl::opt<FunctionNameKind> ClPrintFunctions(
     "functions", cl::init(FunctionNameKind::LinkageName),
-    cl::desc("Print function name for a given address:"),
+    cl::desc("Print function name for a given address:"), cl::ValueOptional,
     cl::values(clEnumValN(FunctionNameKind::None, "none", "omit function name"),
                clEnumValN(FunctionNameKind::ShortName, "short",
                           "print short function name"),
                clEnumValN(FunctionNameKind::LinkageName, "linkage",
-                          "print function linkage name")));
+                          "print function linkage name (default)"),
+               // Sentinel value for unspecified value.
+               clEnumValN(FunctionNameKind::LinkageName, "", "")));
+static cl::alias ClPrintFunctionsShort("f", cl::desc("Alias for -functions"),
+                                       cl::NotHidden,
+                                       cl::aliasopt(ClPrintFunctions));
 
 static cl::opt<bool>
     ClUseRelativeAddress("relative-address", cl::init(false),