Index: docs/UsersManual.rst
===================================================================
--- docs/UsersManual.rst
+++ docs/UsersManual.rst
@@ -1855,6 +1855,27 @@
   must come first.)
 
 
+Controlling LLVM IR Output
+---------------------------
+
+Controlling Values Names in LLVM IR
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+Emitting value names in LLVM IR increases the size and verbosity of the IR.
+By default value names are only emitted in assertion enabled builds of Clang.
+However, when reading IR it can be useful to re-enable the emission of value
+names to improve readability.
+
+.. option:: -fdiscard-value-names
+
+  Discard value names when generating LLVM IR.
+
+.. option:: -fno-discard-value-names
+
+  Do not discard value names when generating LLVM IR. This option can be used
+  to re-enable names for release builds of Clang.
+
+
 Comment Parsing Options
 -----------------------
 
Index: include/clang/Driver/Options.td
===================================================================
--- include/clang/Driver/Options.td
+++ include/clang/Driver/Options.td
@@ -790,6 +790,10 @@
     HelpText<"Print a template comparison tree for differing templates">;
 def fdeclspec : Flag<["-"], "fdeclspec">, Group<f_clang_Group>,
   HelpText<"Allow __declspec as a keyword">, Flags<[CC1Option]>;
+def fdiscard_value_names : Flag<["-"], "fdiscard-value-names">, Group<f_clang_Group>,
+  HelpText<"Discard value names in LLVM IR">, Flags<[DriverOption]>;
+def fno_discard_value_names : Flag<["-"], "fno-discard-value-names">, Group<f_clang_Group>,
+  HelpText<"Do not discard value names in LLVM IR">, Flags<[DriverOption]>;
 def fdollars_in_identifiers : Flag<["-"], "fdollars-in-identifiers">, Group<f_Group>,
   HelpText<"Allow '$' in identifiers">, Flags<[CC1Option]>;
 def fdwarf2_cfi_asm : Flag<["-"], "fdwarf2-cfi-asm">, Group<clang_ignored_f_Group>;
Index: lib/Driver/ToolChains/Clang.cpp
===================================================================
--- lib/Driver/ToolChains/Clang.cpp
+++ lib/Driver/ToolChains/Clang.cpp
@@ -3266,12 +3266,23 @@
   if (!C.isForDiagnostics())
     CmdArgs.push_back("-disable-free");
 
-// Disable the verification pass in -asserts builds.
+  const bool IsAssertBuild =
 #ifdef NDEBUG
-  CmdArgs.push_back("-disable-llvm-verifier");
-  // Discard LLVM value names in -asserts builds.
-  CmdArgs.push_back("-discard-value-names");
+      true;
+#else
+      false;
 #endif
+  // Disable the verification pass in -asserts builds.
+  if (IsAssertBuild)
+    CmdArgs.push_back("disable-llvm-verifier");
+
+  // Discard value names in assert builds unless otherwise specified.
+  if (const Arg *A = Args.getLastArg(options::OPT_fdiscard_value_names,
+                                     options::OPT_fno_discard_value_names)) {
+    if (A->getOption().matches(options::OPT_fdiscard_value_names))
+      CmdArgs.push_back("-discard-value-names");
+  } else if (IsAssertBuild)
+    CmdArgs.push_back("-discard-value-names");
 
   // Set the main file name, so that debug info works even with
   // -save-temps.
Index: test/Driver/clang_f_opts.c
===================================================================
--- test/Driver/clang_f_opts.c
+++ test/Driver/clang_f_opts.c
@@ -517,3 +517,8 @@
 // RUN: %clang -### -S %s 2>&1 | FileCheck -check-prefix=CHECK-NO-CF-PROTECTION-BRANCH %s
 // CHECK-CF-PROTECTION-BRANCH: -fcf-protection=branch
 // CHECK-NO-CF-PROTECTION-BRANCH-NOT: -fcf-protection=branch
+
+// RUN: %clang -### -S -fdiscard-value-names %s 2>&1 | FileCheck -check-prefix=CHECK-DISCARD-NAMES %s
+// RUN: %clang -### -S -fno-discard-value-names %s 2>&1 | FileCheck -check-prefix=CHECK-NO-DISCARD-NAMES %s
+// CHECK-DISCARD-NAMES: "-discard-value-names"
+// CHECK-NO-DISCARD-NAMES-NOT: "-discard-value-names"