diff --git a/include/clang/Basic/DiagnosticDriverKinds.td b/include/clang/Basic/DiagnosticDriverKinds.td
index 3e5e0a8a02e526f804f5dcd9f343320285d0c5e2..2a057f8050bd498b2d6d10bcf4a3f25a3dcf6885 100644
--- a/include/clang/Basic/DiagnosticDriverKinds.td
+++ b/include/clang/Basic/DiagnosticDriverKinds.td
@@ -138,9 +138,10 @@ def err_drv_cc_print_options_failure : Error<
 def err_drv_lto_without_lld : Error<"LTO requires -fuse-ld=lld">;
 def err_drv_preamble_format : Error<
     "incorrect format for -preamble-bytes=N,END">;
-def err_invalid_ios_deployment_target : Error<
+def warn_invalid_ios_deployment_target : Warning<
   "invalid iOS deployment version '%0', iOS 10 is the maximum deployment "
-  "target for 32-bit targets">;
+  "target for 32-bit targets">, InGroup<InvalidIOSDeploymentTarget>,
+  DefaultError;
 def err_drv_conflicting_deployment_targets : Error<
   "conflicting deployment targets, both '%0' and '%1' are present in environment">;
 def err_arc_unsupported_on_runtime : Error<
diff --git a/include/clang/Basic/DiagnosticGroups.td b/include/clang/Basic/DiagnosticGroups.td
index 9823316cc9262e2e4015d7c5adab87c571f07000..1b102ba7269ea12e6391a0101c5a1efb5ac0a5a5 100644
--- a/include/clang/Basic/DiagnosticGroups.td
+++ b/include/clang/Basic/DiagnosticGroups.td
@@ -153,6 +153,9 @@ def GNUFlexibleArrayUnionMember : DiagGroup<"gnu-flexible-array-union-member">;
 def GNUFoldingConstant : DiagGroup<"gnu-folding-constant">;
 def FormatExtraArgs : DiagGroup<"format-extra-args">;
 def FormatZeroLength : DiagGroup<"format-zero-length">;
+
+def InvalidIOSDeploymentTarget : DiagGroup<"invalid-ios-deployment-target">;
+
 def CXX1zCompatMangling : DiagGroup<"c++1z-compat-mangling">;
 // Name of this warning in GCC.
 def NoexceptType : DiagGroup<"noexcept-type", [CXX1zCompatMangling]>;
diff --git a/lib/Driver/ToolChains/Darwin.cpp b/lib/Driver/ToolChains/Darwin.cpp
index 5f2b855b0c8258f2e2c07f1244640bd3c2ed3710..5db6238b136e7cc391d167c673d6ddf29f179c79 100644
--- a/lib/Driver/ToolChains/Darwin.cpp
+++ b/lib/Driver/ToolChains/Darwin.cpp
@@ -1179,7 +1179,7 @@ void Darwin::AddDeploymentTarget(DerivedArgList &Args) const {
       Driver::GetReleaseVersion(iOSVersion->getValue(), Major, Minor, Micro,
                                 HadExtra) &&
       Major > 10)
-    getDriver().Diag(diag::err_invalid_ios_deployment_target)
+    getDriver().Diag(diag::warn_invalid_ios_deployment_target)
         << iOSVersion->getAsString(Args);
 
   // Add a macro to differentiate between m(iphone|tv|watch)os-version-min=X.Y and
@@ -1228,7 +1228,7 @@ void Darwin::AddDeploymentTarget(DerivedArgList &Args) const {
         Driver::GetReleaseVersion(iOSTarget.c_str(), Major, Minor, Micro,
                                   HadExtra) &&
         Major > 10)
-      getDriver().Diag(diag::err_invalid_ios_deployment_target)
+      getDriver().Diag(diag::warn_invalid_ios_deployment_target)
           << std::string("IPHONEOS_DEPLOYMENT_TARGET=") + iOSTarget;
 
     // If there is no command-line argument to specify the Target version and
@@ -1298,6 +1298,15 @@ void Darwin::AddDeploymentTarget(DerivedArgList &Args) const {
           break;
         case llvm::Triple::IOS:
           getTriple().getiOSVersion(Major, Minor, Micro);
+
+          // iOS 10 is the maximum deployment target for 32-bit targets. If the
+          // inferred deployment target is iOS 11 or later, set it to 10.99.
+          if (getTriple().isArch32Bit() && Major >= 11) {
+            Major = 10;
+            Minor = 99;
+            Micro = 99;
+          }
+
           OSTarget = &iOSTarget;
           break;
         case llvm::Triple::TvOS:
@@ -1393,13 +1402,6 @@ void Darwin::AddDeploymentTarget(DerivedArgList &Args) const {
         HadExtra || Major >= 100 || Minor >= 100 || Micro >= 100)
       getDriver().Diag(diag::err_drv_invalid_version_number)
           << iOSVersion->getAsString(Args);
-    // iOS 10 is the maximum deployment target for 32-bit targets. If the
-    // inferred deployment target is iOS 11 or later, set it to 10.99.
-    if (getTriple().isArch32Bit() && Major >= 11) {
-      Major = 10;
-      Minor = 99;
-      Micro = 99;
-    }
   } else if (Platform == TvOS) {
     if (!Driver::GetReleaseVersion(TvOSVersion->getValue(), Major, Minor,
                                    Micro, HadExtra) || HadExtra ||
diff --git a/test/Driver/darwin-version.c b/test/Driver/darwin-version.c
index 12c7ef6eb0b18dc38096080db501d599a19a28f1..785bd8ae98c80d9bed0c1e22ff9c6d7188e197a3 100644
--- a/test/Driver/darwin-version.c
+++ b/test/Driver/darwin-version.c
@@ -45,6 +45,10 @@
 // RUN: FileCheck --check-prefix=CHECK-VERSION-IOS11 %s
 // CHECK-VERSION-IOS11: arm64-apple-ios11.1.0
 
+// RUN: %clang -target armv7-apple-ios9.0 -miphoneos-version-min=11.0 -c -Wno-invalid-ios-deployment-target -### %s 2>&1 | \
+// RUN: FileCheck --check-prefix=CHECK-VERSION-IOS12 %s
+// CHECK-VERSION-IOS12: thumbv7-apple-ios11.0.0
+
 // RUN: %clang -target i686-apple-darwin8 -c %s -### 2>&1 | \
 // RUN:   FileCheck --check-prefix=CHECK-VERSION-OSX4 %s
 // RUN: %clang -target i686-apple-darwin9 -mmacosx-version-min=10.4 -c %s -### 2>&1 | \