Index: include/clang/Driver/Options.td
===================================================================
--- include/clang/Driver/Options.td
+++ include/clang/Driver/Options.td
@@ -1379,6 +1379,9 @@
   Flags<[HelpHidden]>;
 def mglibc : Flag<["-"], "mglibc">, Group<m_libc_Group>, Flags<[HelpHidden]>;
 def muclibc : Flag<["-"], "muclibc">, Group<m_libc_Group>, Flags<[HelpHidden]>;
+def mmin_libc_version_EQ : Joined<["-"], "mmin-libc-version=">,
+                           Group<m_libc_Group>,
+                           Flags<[ DriverOption, CC1Option ]>;
 def module_file_info : Flag<["-"], "module-file-info">, Flags<[DriverOption,CC1Option]>, Group<Action_Group>;
 def mthumb : Flag<["-"], "mthumb">, Group<m_Group>;
 def mtune_EQ : Joined<["-"], "mtune=">, Group<m_Group>;
Index: include/clang/Frontend/CodeGenOptions.def
===================================================================
--- include/clang/Frontend/CodeGenOptions.def
+++ include/clang/Frontend/CodeGenOptions.def
@@ -162,6 +162,9 @@
 /// The default TLS model to use.
 ENUM_CODEGENOPT(DefaultTLSModel, TLSModel, 2, GeneralDynamicTLSModel)
 
+/// minimum libc version
+VALUE_CODEGENOPT(MinCLibVer, 32, 0)
+
 #undef CODEGENOPT
 #undef ENUM_CODEGENOPT
 #undef VALUE_CODEGENOPT
Index: lib/CodeGen/CodeGenModule.cpp
===================================================================
--- lib/CodeGen/CodeGenModule.cpp
+++ lib/CodeGen/CodeGenModule.cpp
@@ -372,6 +372,10 @@
     getModule().addModuleFlag(llvm::Module::Warning, "Debug Info Version",
                               llvm::DEBUG_METADATA_VERSION);
 
+  if (CodeGenOpts.MinCLibVer)
+    getModule().addModuleFlag(llvm::Module::Warning, "minimum libc version",
+                              CodeGenOpts.MinCLibVer);
+
   // We need to record the widths of enums and wchar_t, so that we can generate
   // the correct build attributes in the ARM backend.
   llvm::Triple::ArchType Arch = Context.getTargetInfo().getTriple().getArch();
Index: lib/Driver/Tools.cpp
===================================================================
--- lib/Driver/Tools.cpp
+++ lib/Driver/Tools.cpp
@@ -4121,6 +4121,12 @@
       CmdArgs.push_back(Args.MakeArgString("-fms-compatibility-version=" + Ver));
   }
 
+  // -mmin-libc-version
+  if (const Arg *A = Args.getLastArg(options::OPT_mmin_libc_version_EQ)) {
+    std::string Version = A->getValue();
+    CmdArgs.push_back(Args.MakeArgString("-mmin-libc-version=" + Version));
+  }
+
   // -fno-borland-extensions is default.
   if (Args.hasFlag(options::OPT_fborland_extensions,
                    options::OPT_fno_borland_extensions, false))
Index: lib/Frontend/CompilerInvocation.cpp
===================================================================
--- lib/Frontend/CompilerInvocation.cpp
+++ lib/Frontend/CompilerInvocation.cpp
@@ -565,6 +565,27 @@
     }
   }
 
+  if (Arg *A = Args.getLastArg(OPT_mmin_libc_version_EQ)) {
+    StringRef Version = A->getValue();
+
+    unsigned VC[3] = {0};
+    SmallVector<StringRef, 3> Components;
+
+    Version.split(Components, ".", llvm::array_lengthof(VC));
+    for (unsigned CI = 0,
+                  CE = std::min(Components.size(), llvm::array_lengthof(VC));
+         CI < CE; ++CI) {
+      if (Components[CI].getAsInteger(10, VC[CI])) {
+        Diags.Report(diag::err_drv_invalid_value) << A->getAsString(Args)
+                                                  << Version;
+        memset(VC, 0, sizeof(VC));
+        break;
+      }
+    }
+
+    Opts.MinCLibVer = VC[0] * 10000 + VC[1] * 100 + VC[2];
+  }
+
   if (Arg *A = Args.getLastArg(OPT_ffp_contract)) {
     StringRef Val = A->getValue();
     if (Val == "fast")
Index: test/CodeGen/libc-version.c
===================================================================
--- /dev/null
+++ test/CodeGen/libc-version.c
@@ -0,0 +1,13 @@
+// RUN: %clang_cc1 -triple thumbv7-windows-itanium -mmin-libc-version=12.0 -emit-llvm -o - %s \
+// RUN:    | FileCheck %s -check-prefix CHECK-WINDOWS
+// RUN: %clang_cc1 -triple thumbv7-windows-itanium -emit-llvm -o - %s \
+// RUN:    | FileCheck %s
+// RUN: %clang_cc1 -triple i686-linux-gnu -mmin-libc-version=2.21.0 -emit-llvm -o - %s \
+// RUN:    | FileCheck %s -check-prefix CHECK-LINUX
+// RUN: %clang_cc1 -triple i686-linux-gnu -emit-llvm -o - %s \
+// RUN:    | FileCheck %s
+
+// CHECK-LINUX: !"minimum libc version", i32 22100}
+// CHECK-WINDOWS: !"minimum libc version", i32 120000}
+// CHECK-NOT: !"minimum libc version"
+