diff --git a/cc/androidmk.go b/cc/androidmk.go
index ef695b0..19c7182 100644
--- a/cc/androidmk.go
+++ b/cc/androidmk.go
@@ -29,6 +29,7 @@
 	vendorSuffix       = ".vendor"
 	ramdiskSuffix      = ".ramdisk"
 	recoverySuffix     = ".recovery"
+	sdkSuffix          = ".sdk"
 )
 
 type AndroidMkContext interface {
@@ -103,6 +104,28 @@
 						}
 					}
 				}
+				if c.Properties.IsSdkVariant && c.Properties.SdkAndPlatformVariantVisibleToMake {
+					// Make the SDK variant uninstallable so that there are not two rules to install
+					// to the same location.
+					entries.SetBool("LOCAL_UNINSTALLABLE_MODULE", true)
+					// Add the unsuffixed name to SOONG_SDK_VARIANT_MODULES so that Make can rewrite
+					// dependencies to the .sdk suffix when building a module that uses the SDK.
+					entries.SetString("SOONG_SDK_VARIANT_MODULES",
+						"$(SOONG_SDK_VARIANT_MODULES) $(patsubst %.sdk,%,$(LOCAL_MODULE))")
+				}
+			},
+		},
+		ExtraFooters: []android.AndroidMkExtraFootersFunc{
+			func(w io.Writer, name, prefix, moduleDir string, entries *android.AndroidMkEntries) {
+				if c.Properties.IsSdkVariant && c.Properties.SdkAndPlatformVariantVisibleToMake &&
+					c.CcLibraryInterface() && c.Shared() {
+					// Using the SDK variant as a JNI library needs a copy of the .so that
+					// is not named .sdk.so so that it can be packaged into the APK with
+					// the right name.
+					fmt.Fprintln(w, "$(eval $(call copy-one-file,",
+						"$(LOCAL_BUILT_MODULE),",
+						"$(patsubst %.sdk.so,%.so,$(LOCAL_BUILT_MODULE))))")
+				}
 			},
 		},
 	}
@@ -393,6 +416,9 @@
 }
 
 func (installer *baseInstaller) AndroidMkEntries(ctx AndroidMkContext, entries *android.AndroidMkEntries) {
+	if installer.path == (android.InstallPath{}) {
+		return
+	}
 	// Soong installation is only supported for host modules. Have Make
 	// installation trigger Soong installation.
 	if ctx.Target().Os.Class == android.Host {
diff --git a/cc/cc.go b/cc/cc.go
index 037b99c..794adf1 100644
--- a/cc/cc.go
+++ b/cc/cc.go
@@ -42,6 +42,7 @@
 	ctx.RegisterModuleType("cc_defaults", defaultsFactory)
 
 	ctx.PreDepsMutators(func(ctx android.RegisterMutatorsContext) {
+		ctx.BottomUp("sdk", sdkMutator).Parallel()
 		ctx.BottomUp("vndk", VndkMutator).Parallel()
 		ctx.BottomUp("link", LinkageMutator).Parallel()
 		ctx.BottomUp("ndk_api", NdkApiMutator).Parallel()
@@ -208,9 +209,13 @@
 	// Deprecated. true is the default, false is invalid.
 	Clang *bool `android:"arch_variant"`
 
-	// Minimum sdk version supported when compiling against the ndk
+	// Minimum sdk version supported when compiling against the ndk. Setting this property causes
+	// two variants to be built, one for the platform and one for apps.
 	Sdk_version *string
 
+	// If true, always create an sdk variant and don't create a platform variant.
+	Sdk_variant_only *bool
+
 	AndroidMkSharedLibs       []string `blueprint:"mutated"`
 	AndroidMkStaticLibs       []string `blueprint:"mutated"`
 	AndroidMkRuntimeLibs      []string `blueprint:"mutated"`
@@ -252,6 +257,16 @@
 	SnapshotRuntimeLibs []string `blueprint:"mutated"`
 
 	Installable *bool
+
+	// Set by factories of module types that can only be referenced from variants compiled against
+	// the SDK.
+	AlwaysSdk bool `blueprint:"mutated"`
+
+	// Variant is an SDK variant created by sdkMutator
+	IsSdkVariant bool `blueprint:"mutated"`
+	// Set when both SDK and platform variants are exported to Make to trigger renaming the SDK
+	// variant to have a ".sdk" suffix.
+	SdkAndPlatformVariantVisibleToMake bool `blueprint:"mutated"`
 }
 
 type VendorProperties struct {
@@ -527,7 +542,10 @@
 }
 
 func (c *Module) SelectedStl() string {
-	return c.stl.Properties.SelectedStl
+	if c.stl != nil {
+		return c.stl.Properties.SelectedStl
+	}
+	return ""
 }
 
 func (c *Module) ToolchainLibrary() bool {
@@ -555,6 +573,10 @@
 	return String(c.Properties.Sdk_version)
 }
 
+func (c *Module) AlwaysSdk() bool {
+	return c.Properties.AlwaysSdk || Bool(c.Properties.Sdk_variant_only)
+}
+
 func (c *Module) IncludeDirs() android.Paths {
 	if c.linker != nil {
 		if library, ok := c.linker.(exportedFlagsProducer); ok {
@@ -803,6 +825,17 @@
 	return c.Properties.VndkVersion != ""
 }
 
+func (c *Module) canUseSdk() bool {
+	return c.Os() == android.Android && !c.UseVndk() && !c.InRamdisk() && !c.InRecovery()
+}
+
+func (c *Module) UseSdk() bool {
+	if c.canUseSdk() {
+		return String(c.Properties.Sdk_version) != ""
+	}
+	return false
+}
+
 func (c *Module) isCoverageVariant() bool {
 	return c.coverage.Properties.IsCoverageVariant
 }
@@ -1060,14 +1093,11 @@
 }
 
 func (ctx *moduleContextImpl) canUseSdk() bool {
-	return ctx.ctx.Device() && !ctx.useVndk() && !ctx.inRamdisk() && !ctx.inRecovery() && !ctx.ctx.Fuchsia()
+	return ctx.mod.canUseSdk()
 }
 
 func (ctx *moduleContextImpl) useSdk() bool {
-	if ctx.canUseSdk() {
-		return String(ctx.mod.Properties.Sdk_version) != ""
-	}
-	return false
+	return ctx.mod.UseSdk()
 }
 
 func (ctx *moduleContextImpl) sdkVersion() string {
@@ -1386,6 +1416,8 @@
 		c.Properties.SubName += ramdiskSuffix
 	} else if c.InRecovery() && !c.OnlyInRecovery() {
 		c.Properties.SubName += recoverySuffix
+	} else if c.Properties.IsSdkVariant && c.Properties.SdkAndPlatformVariantVisibleToMake {
+		c.Properties.SubName += sdkSuffix
 	}
 
 	ctx := &moduleContext{
diff --git a/cc/genrule.go b/cc/genrule.go
index 155e410..9331448 100644
--- a/cc/genrule.go
+++ b/cc/genrule.go
@@ -27,6 +27,7 @@
 	Vendor_available   *bool
 	Ramdisk_available  *bool
 	Recovery_available *bool
+	Sdk_version        *string
 }
 
 // cc_genrule is a genrule that can depend on other cc_* objects.
diff --git a/cc/library.go b/cc/library.go
index 346e7d8..5ce854e 100644
--- a/cc/library.go
+++ b/cc/library.go
@@ -1223,7 +1223,7 @@
 	if Bool(library.Properties.Static_ndk_lib) && library.static() &&
 		!ctx.useVndk() && !ctx.inRamdisk() && !ctx.inRecovery() && ctx.Device() &&
 		library.baseLinker.sanitize.isUnsanitizedVariant() &&
-		!library.buildStubs() {
+		!library.buildStubs() && ctx.sdkVersion() == "" {
 		installPath := getNdkSysrootBase(ctx).Join(
 			ctx, "usr/lib", config.NDKTriple(ctx.toolchain()), file.Base())
 
diff --git a/cc/linkable.go b/cc/linkable.go
index 80cd6b8..fbe61a4 100644
--- a/cc/linkable.go
+++ b/cc/linkable.go
@@ -45,12 +45,14 @@
 	InRecovery() bool
 	OnlyInRecovery() bool
 
+	UseSdk() bool
 	UseVndk() bool
 	MustUseVendorVariant() bool
 	IsVndk() bool
 	HasVendorVariant() bool
 
 	SdkVersion() string
+	AlwaysSdk() bool
 
 	ToolchainLibrary() bool
 	NdkPrebuiltStl() bool
diff --git a/cc/linker.go b/cc/linker.go
index ae5ee0a..385e04e 100644
--- a/cc/linker.go
+++ b/cc/linker.go
@@ -158,6 +158,13 @@
 			// the ramdisk variant of the C/C++ module.
 			Exclude_static_libs []string
 		}
+		Platform struct {
+			// list of shared libs that should be use to build the platform variant
+			// of a module that sets sdk_version.  This should rarely be necessary,
+			// in most cases the same libraries are available for the SDK and platform
+			// variants.
+			Shared_libs []string
+		}
 	}
 
 	// make android::build:GetBuildNumber() available containing the build ID.
@@ -255,6 +262,10 @@
 		deps.WholeStaticLibs = removeListFromList(deps.WholeStaticLibs, linker.Properties.Target.Recovery.Exclude_static_libs)
 	}
 
+	if !ctx.useSdk() {
+		deps.SharedLibs = append(deps.SharedLibs, linker.Properties.Target.Platform.Shared_libs...)
+	}
+
 	if ctx.toolchain().Bionic() {
 		// libclang_rt.builtins and libatomic have to be last on the command line
 		if !Bool(linker.Properties.No_libcrt) {
diff --git a/cc/ndk_library.go b/cc/ndk_library.go
index 2a86d33..68d4ac0 100644
--- a/cc/ndk_library.go
+++ b/cc/ndk_library.go
@@ -381,6 +381,9 @@
 	module.linker = stub
 	module.installer = stub
 
+	module.Properties.AlwaysSdk = true
+	module.Properties.Sdk_version = StringPtr("current")
+
 	module.AddProperties(&stub.properties, &library.MutatedProperties)
 
 	return module
diff --git a/cc/ndk_prebuilt.go b/cc/ndk_prebuilt.go
index e849aee..f909add 100644
--- a/cc/ndk_prebuilt.go
+++ b/cc/ndk_prebuilt.go
@@ -76,6 +76,8 @@
 			baseLinker: NewBaseLinker(nil),
 		},
 	}
+	module.Properties.AlwaysSdk = true
+	module.Properties.Sdk_version = StringPtr("current")
 	module.Properties.HideFromMake = true
 	return module.Init()
 }
@@ -115,10 +117,9 @@
 		libraryDecorator: library,
 	}
 	module.installer = nil
-	minVersionString := "minimum"
-	noStlString := "none"
-	module.Properties.Sdk_version = &minVersionString
-	module.stl.Properties.Stl = &noStlString
+	module.Properties.Sdk_version = StringPtr("minimum")
+	module.Properties.AlwaysSdk = true
+	module.stl.Properties.Stl = StringPtr("none")
 	return module.Init()
 }
 
@@ -135,6 +136,9 @@
 	}
 	module.installer = nil
 	module.Properties.HideFromMake = true
+	module.Properties.AlwaysSdk = true
+	module.Properties.Sdk_version = StringPtr("current")
+	module.stl.Properties.Stl = StringPtr("none")
 	module.ModuleBase.EnableNativeBridgeSupportByDefault()
 	return module.Init()
 }
diff --git a/cc/sdk.go b/cc/sdk.go
new file mode 100644
index 0000000..d05a04a
--- /dev/null
+++ b/cc/sdk.go
@@ -0,0 +1,65 @@
+// Copyright 2020 Google Inc. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package cc
+
+import (
+	"android/soong/android"
+	"android/soong/genrule"
+)
+
+// sdkMutator sets a creates a platform and an SDK variant for modules
+// that set sdk_version, and ignores sdk_version for the platform
+// variant.  The SDK variant will be used for embedding in APKs
+// that may be installed on older platforms.  Apexes use their own
+// variants that enforce backwards compatibility.
+func sdkMutator(ctx android.BottomUpMutatorContext) {
+	if ctx.Os() != android.Android {
+		return
+	}
+
+	switch m := ctx.Module().(type) {
+	case LinkableInterface:
+		if m.AlwaysSdk() {
+			if !m.UseSdk() {
+				ctx.ModuleErrorf("UseSdk() must return true when AlwaysSdk is set, did the factory forget to set Sdk_version?")
+			}
+			ctx.CreateVariations("sdk")
+		} else if m.UseSdk() {
+			modules := ctx.CreateVariations("", "sdk")
+			modules[0].(*Module).Properties.Sdk_version = nil
+			modules[1].(*Module).Properties.IsSdkVariant = true
+
+			if ctx.Config().UnbundledBuild() {
+				modules[0].(*Module).Properties.HideFromMake = true
+			} else {
+				modules[1].(*Module).Properties.SdkAndPlatformVariantVisibleToMake = true
+				modules[1].(*Module).Properties.PreventInstall = true
+			}
+			ctx.AliasVariation("")
+		} else {
+			ctx.CreateVariations("")
+			ctx.AliasVariation("")
+		}
+	case *genrule.Module:
+		if p, ok := m.Extra.(*GenruleExtraProperties); ok {
+			if String(p.Sdk_version) != "" {
+				ctx.CreateVariations("", "sdk")
+			} else {
+				ctx.CreateVariations("")
+			}
+			ctx.AliasVariation("")
+		}
+	}
+}
diff --git a/cc/sdk_test.go b/cc/sdk_test.go
new file mode 100644
index 0000000..5a3c181
--- /dev/null
+++ b/cc/sdk_test.go
@@ -0,0 +1,102 @@
+// Copyright 2020 Google Inc. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package cc
+
+import (
+	"testing"
+
+	"android/soong/android"
+)
+
+func TestSdkMutator(t *testing.T) {
+	bp := `
+		cc_library {
+			name: "libsdk",
+			shared_libs: ["libsdkdep"],
+			sdk_version: "current",
+			stl: "c++_shared",
+		}
+
+		cc_library {
+			name: "libsdkdep",
+			sdk_version: "current",
+			stl: "c++_shared",
+		}
+
+		cc_library {
+			name: "libplatform",
+			shared_libs: ["libsdk"],
+			stl: "libc++",
+		}
+
+		cc_binary {
+			name: "platformbinary",
+			shared_libs: ["libplatform"],
+			stl: "libc++",
+		}
+
+		cc_binary {
+			name: "sdkbinary",
+			shared_libs: ["libsdk"],
+			sdk_version: "current",
+			stl: "libc++",
+		}
+	`
+
+	assertDep := func(t *testing.T, from, to android.TestingModule) {
+		t.Helper()
+		found := false
+
+		var toFile android.Path
+		m := to.Module().(*Module)
+		if toc := m.Toc(); toc.Valid() {
+			toFile = toc.Path()
+		} else {
+			toFile = m.outputFile.Path()
+		}
+
+		rule := from.Description("link")
+		for _, dep := range rule.Implicits {
+			if dep.String() == toFile.String() {
+				found = true
+			}
+		}
+		if !found {
+			t.Errorf("expected %q in %q", toFile.String(), rule.Implicits.Strings())
+		}
+	}
+
+	ctx := testCc(t, bp)
+
+	libsdkNDK := ctx.ModuleForTests("libsdk", "android_arm64_armv8-a_sdk_shared")
+	libsdkPlatform := ctx.ModuleForTests("libsdk", "android_arm64_armv8-a_shared")
+	libsdkdepNDK := ctx.ModuleForTests("libsdkdep", "android_arm64_armv8-a_sdk_shared")
+	libsdkdepPlatform := ctx.ModuleForTests("libsdkdep", "android_arm64_armv8-a_shared")
+	libplatform := ctx.ModuleForTests("libplatform", "android_arm64_armv8-a_shared")
+	platformbinary := ctx.ModuleForTests("platformbinary", "android_arm64_armv8-a")
+	sdkbinary := ctx.ModuleForTests("sdkbinary", "android_arm64_armv8-a_sdk")
+
+	libcxxNDK := ctx.ModuleForTests("ndk_libc++_shared", "android_arm64_armv8-a_sdk_shared")
+	libcxxPlatform := ctx.ModuleForTests("libc++", "android_arm64_armv8-a_shared")
+
+	assertDep(t, libsdkNDK, libsdkdepNDK)
+	assertDep(t, libsdkPlatform, libsdkdepPlatform)
+	assertDep(t, libplatform, libsdkPlatform)
+	assertDep(t, platformbinary, libplatform)
+	assertDep(t, sdkbinary, libsdkNDK)
+
+	assertDep(t, libsdkNDK, libcxxNDK)
+	assertDep(t, libsdkPlatform, libcxxPlatform)
+}
diff --git a/cc/stl.go b/cc/stl.go
index 8113f72..4e74c7f 100644
--- a/cc/stl.go
+++ b/cc/stl.go
@@ -115,9 +115,13 @@
 			switch s {
 			case "libc++", "libc++_static":
 				return s
+			case "c++_shared":
+				return "libc++"
+			case "c++_static":
+				return "libc++_static"
 			case "none":
 				return ""
-			case "":
+			case "", "system":
 				if ctx.static() {
 					return "libc++_static"
 				} else {
diff --git a/cc/testing.go b/cc/testing.go
index b8a7eab..89a9c36 100644
--- a/cc/testing.go
+++ b/cc/testing.go
@@ -138,6 +138,7 @@
 			name: "libgcc_stripped",
 			vendor_available: true,
 			recovery_available: true,
+			sdk_version: "current",
 			src: "",
 		}
 
@@ -155,6 +156,7 @@
 		llndk_library {
 			name: "libc",
 			symbol_file: "",
+			sdk_version: "current",
 		}
 		cc_library {
 			name: "libm",
@@ -174,6 +176,7 @@
 		llndk_library {
 			name: "libm",
 			symbol_file: "",
+			sdk_version: "current",
 		}
 		cc_library {
 			name: "libdl",
@@ -193,6 +196,7 @@
 		llndk_library {
 			name: "libdl",
 			symbol_file: "",
+			sdk_version: "current",
 		}
 		cc_library {
 			name: "libft2",
@@ -205,6 +209,7 @@
 			name: "libft2",
 			symbol_file: "",
 			vendor_available: false,
+			sdk_version: "current",
 		}
 		cc_library {
 			name: "libc++_static",
@@ -336,6 +341,16 @@
 			sdk_version: "27",
 		}
 
+		ndk_prebuilt_object {
+			name: "ndk_crtbegin_dynamic.27",
+			sdk_version: "27",
+		}
+
+		ndk_prebuilt_object {
+			name: "ndk_crtend_android.27",
+			sdk_version: "27",
+		}
+
 		ndk_prebuilt_shared_stl {
 			name: "ndk_libc++_shared",
 		}
diff --git a/cc/toolchain_library.go b/cc/toolchain_library.go
index dfc6f76..042e012 100644
--- a/cc/toolchain_library.go
+++ b/cc/toolchain_library.go
@@ -67,6 +67,7 @@
 	module.stl = nil
 	module.sanitize = nil
 	module.installer = nil
+	module.Properties.Sdk_version = StringPtr("current")
 	return module.Init()
 }