diff --git a/BUILD b/BUILD
index 5c05c9e..b066f38 100644
--- a/BUILD
+++ b/BUILD
@@ -78,7 +78,7 @@
 
 core_version = "7.0.0"
 
-version = "1.21.0-dev"
+version = "1.21.0-pre1"
 
 GPR_PUBLIC_HDRS = [
     "include/grpc/support/alloc.h",
diff --git a/CMakeLists.txt b/CMakeLists.txt
index accc288..f0c1487 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -24,7 +24,7 @@
 cmake_minimum_required(VERSION 2.8)
 
 set(PACKAGE_NAME      "grpc")
-set(PACKAGE_VERSION   "1.21.0-dev")
+set(PACKAGE_VERSION   "1.21.0-pre1")
 set(PACKAGE_STRING    "${PACKAGE_NAME} ${PACKAGE_VERSION}")
 set(PACKAGE_TARNAME   "${PACKAGE_NAME}-${PACKAGE_VERSION}")
 set(PACKAGE_BUGREPORT "https://github.com/grpc/grpc/issues/")
diff --git a/Makefile b/Makefile
index c4a6222..b68529b 100644
--- a/Makefile
+++ b/Makefile
@@ -460,8 +460,8 @@
 endif
 
 CORE_VERSION = 7.0.0
-CPP_VERSION = 1.21.0-dev
-CSHARP_VERSION = 1.21.0-dev
+CPP_VERSION = 1.21.0-pre1
+CSHARP_VERSION = 1.21.0-pre1
 
 CPPFLAGS_NO_ARCH += $(addprefix -I, $(INCLUDES)) $(addprefix -D, $(DEFINES))
 CPPFLAGS += $(CPPFLAGS_NO_ARCH) $(ARCH_FLAGS)
diff --git a/build.yaml b/build.yaml
index fabb041..3b40102 100644
--- a/build.yaml
+++ b/build.yaml
@@ -14,7 +14,7 @@
   '#10': See the expand_version.py for all the quirks here
   core_version: 7.0.0
   g_stands_for: gandalf
-  version: 1.21.0-dev
+  version: 1.21.0-pre1
 filegroups:
 - name: alts_proto
   headers:
diff --git a/doc/g_stands_for.md b/doc/g_stands_for.md
index b926db1..ba0ba58f 100644
--- a/doc/g_stands_for.md
+++ b/doc/g_stands_for.md
@@ -20,4 +20,4 @@
 - 1.18 'g' stands for ['goose'](https://github.com/grpc/grpc/tree/v1.18.x)
 - 1.19 'g' stands for ['gold'](https://github.com/grpc/grpc/tree/v1.19.x)
 - 1.20 'g' stands for ['godric'](https://github.com/grpc/grpc/tree/v1.20.x)
-- 1.21 'g' stands for ['gandalf'](https://github.com/grpc/grpc/tree/master)
+- 1.21 'g' stands for ['gandalf'](https://github.com/grpc/grpc/tree/v1.21.x)
diff --git a/gRPC-C++.podspec b/gRPC-C++.podspec
index 1dc2258..6f445a7 100644
--- a/gRPC-C++.podspec
+++ b/gRPC-C++.podspec
@@ -23,15 +23,15 @@
 Pod::Spec.new do |s|
   s.name     = 'gRPC-C++'
   # TODO (mxyan): use version that match gRPC version when pod is stabilized
-  # version = '1.21.0-dev'
-  version = '0.0.8-dev'
+  # version = '1.21.0-pre1'
+  version = '0.0.8-pre1'
   s.version  = version
   s.summary  = 'gRPC C++ library'
   s.homepage = 'https://grpc.io'
   s.license  = 'Apache License, Version 2.0'
   s.authors  = { 'The gRPC contributors' => 'grpc-packages@google.com' }
 
-  grpc_version = '1.21.0-dev'
+  grpc_version = '1.21.0-pre1'
 
   s.source = {
     :git => 'https://github.com/grpc/grpc.git',
diff --git a/gRPC-Core.podspec b/gRPC-Core.podspec
index cbf0a4b..3df5539 100644
--- a/gRPC-Core.podspec
+++ b/gRPC-Core.podspec
@@ -22,7 +22,7 @@
 
 Pod::Spec.new do |s|
   s.name     = 'gRPC-Core'
-  version = '1.21.0-dev'
+  version = '1.21.0-pre1'
   s.version  = version
   s.summary  = 'Core cross-platform gRPC library, written in C'
   s.homepage = 'https://grpc.io'
diff --git a/gRPC-ProtoRPC.podspec b/gRPC-ProtoRPC.podspec
index 0e905bd..af515fb 100644
--- a/gRPC-ProtoRPC.podspec
+++ b/gRPC-ProtoRPC.podspec
@@ -21,7 +21,7 @@
 
 Pod::Spec.new do |s|
   s.name     = 'gRPC-ProtoRPC'
-  version = '1.21.0-dev'
+  version = '1.21.0-pre1'
   s.version  = version
   s.summary  = 'RPC library for Protocol Buffers, based on gRPC'
   s.homepage = 'https://grpc.io'
diff --git a/gRPC-RxLibrary.podspec b/gRPC-RxLibrary.podspec
index df86ef7..df8fcae 100644
--- a/gRPC-RxLibrary.podspec
+++ b/gRPC-RxLibrary.podspec
@@ -21,7 +21,7 @@
 
 Pod::Spec.new do |s|
   s.name     = 'gRPC-RxLibrary'
-  version = '1.21.0-dev'
+  version = '1.21.0-pre1'
   s.version  = version
   s.summary  = 'Reactive Extensions library for iOS/OSX.'
   s.homepage = 'https://grpc.io'
diff --git a/gRPC.podspec b/gRPC.podspec
index b3c7a55..5458725 100644
--- a/gRPC.podspec
+++ b/gRPC.podspec
@@ -20,7 +20,7 @@
 
 Pod::Spec.new do |s|
   s.name     = 'gRPC'
-  version = '1.21.0-dev'
+  version = '1.21.0-pre1'
   s.version  = version
   s.summary  = 'gRPC client library for iOS/OSX'
   s.homepage = 'https://grpc.io'
diff --git a/package.xml b/package.xml
index 04d9f35..e058709 100644
--- a/package.xml
+++ b/package.xml
@@ -13,8 +13,8 @@
  <date>2018-01-19</date>
  <time>16:06:07</time>
  <version>
-  <release>1.21.0dev</release>
-  <api>1.21.0dev</api>
+  <release>1.21.0RC1</release>
+  <api>1.21.0RC1</api>
  </version>
  <stability>
   <release>beta</release>
diff --git a/src/cpp/common/version_cc.cc b/src/cpp/common/version_cc.cc
index 166c2d3..8aeb99f 100644
--- a/src/cpp/common/version_cc.cc
+++ b/src/cpp/common/version_cc.cc
@@ -22,5 +22,5 @@
 #include <grpcpp/grpcpp.h>
 
 namespace grpc {
-grpc::string Version() { return "1.21.0-dev"; }
+grpc::string Version() { return "1.21.0-pre1"; }
 }  // namespace grpc
diff --git a/src/csharp/Grpc.Core.Api/VersionInfo.cs b/src/csharp/Grpc.Core.Api/VersionInfo.cs
index 1b2602e..402d251 100644
--- a/src/csharp/Grpc.Core.Api/VersionInfo.cs
+++ b/src/csharp/Grpc.Core.Api/VersionInfo.cs
@@ -38,6 +38,6 @@
         /// <summary>
         /// Current version of gRPC C#
         /// </summary>
-        public const string CurrentVersion = "1.21.0-dev";
+        public const string CurrentVersion = "1.21.0-pre1";
     }
 }
diff --git a/src/csharp/build/dependencies.props b/src/csharp/build/dependencies.props
index b018aac..67647c7 100644
--- a/src/csharp/build/dependencies.props
+++ b/src/csharp/build/dependencies.props
@@ -1,7 +1,7 @@
 <!-- This file is generated -->
 <Project>
   <PropertyGroup>
-    <GrpcCsharpVersion>1.21.0-dev</GrpcCsharpVersion>
+    <GrpcCsharpVersion>1.21.0-pre1</GrpcCsharpVersion>
     <GoogleProtobufVersion>3.7.0</GoogleProtobufVersion>
   </PropertyGroup>
 </Project>
diff --git a/src/csharp/build_unitypackage.bat b/src/csharp/build_unitypackage.bat
index 8c7718f..b8e247f 100644
--- a/src/csharp/build_unitypackage.bat
+++ b/src/csharp/build_unitypackage.bat
@@ -13,7 +13,7 @@
 @rem limitations under the License.
 
 @rem Current package versions
-set VERSION=1.21.0-dev
+set VERSION=1.21.0-pre1
 
 @rem Adjust the location of nuget.exe
 set NUGET=C:\nuget\nuget.exe
diff --git "a/src/objective-c/\041ProtoCompiler-gRPCPlugin.podspec" "b/src/objective-c/\041ProtoCompiler-gRPCPlugin.podspec"
index 88b8d29..d7db869 100644
--- "a/src/objective-c/\041ProtoCompiler-gRPCPlugin.podspec"
+++ "b/src/objective-c/\041ProtoCompiler-gRPCPlugin.podspec"
@@ -42,7 +42,7 @@
   # exclamation mark ensures that other "regular" pods will be able to find it as it'll be installed
   # before them.
   s.name     = '!ProtoCompiler-gRPCPlugin'
-  v = '1.21.0-dev'
+  v = '1.21.0-pre1'
   s.version  = v
   s.summary  = 'The gRPC ProtoC plugin generates Objective-C files from .proto services.'
   s.description = <<-DESC
diff --git a/src/objective-c/GRPCClient/private/version.h b/src/objective-c/GRPCClient/private/version.h
index fcbdfb2..b011dd5 100644
--- a/src/objective-c/GRPCClient/private/version.h
+++ b/src/objective-c/GRPCClient/private/version.h
@@ -22,4 +22,4 @@
 // instead. This file can be regenerated from the template by running
 // `tools/buildgen/generate_projects.sh`.
 
-#define GRPC_OBJC_VERSION_STRING @"1.21.0-dev"
+#define GRPC_OBJC_VERSION_STRING @"1.21.0-pre1"
diff --git a/src/objective-c/tests/version.h b/src/objective-c/tests/version.h
index 87516de..28b4577 100644
--- a/src/objective-c/tests/version.h
+++ b/src/objective-c/tests/version.h
@@ -22,5 +22,5 @@
 // instead. This file can be regenerated from the template by running
 // `tools/buildgen/generate_projects.sh`.
 
-#define GRPC_OBJC_VERSION_STRING @"1.21.0-dev"
+#define GRPC_OBJC_VERSION_STRING @"1.21.0-pre1"
 #define GRPC_C_VERSION_STRING @"7.0.0"
diff --git a/src/php/ext/grpc/version.h b/src/php/ext/grpc/version.h
index 43b3fa6..7d6f86c 100644
--- a/src/php/ext/grpc/version.h
+++ b/src/php/ext/grpc/version.h
@@ -20,6 +20,6 @@
 #ifndef VERSION_H
 #define VERSION_H
 
-#define PHP_GRPC_VERSION "1.21.0dev"
+#define PHP_GRPC_VERSION "1.21.0RC1"
 
 #endif /* VERSION_H */
diff --git a/src/python/grpcio/grpc/_grpcio_metadata.py b/src/python/grpcio/grpc/_grpcio_metadata.py
index 651f8f7..3a9cfc7 100644
--- a/src/python/grpcio/grpc/_grpcio_metadata.py
+++ b/src/python/grpcio/grpc/_grpcio_metadata.py
@@ -14,4 +14,4 @@
 
 # AUTO-GENERATED FROM `$REPO_ROOT/templates/src/python/grpcio/grpc/_grpcio_metadata.py.template`!!!
 
-__version__ = """1.21.0.dev0"""
+__version__ = """1.21.0rc1"""
diff --git a/src/python/grpcio/grpc_version.py b/src/python/grpcio/grpc_version.py
index e430cc2..d843499 100644
--- a/src/python/grpcio/grpc_version.py
+++ b/src/python/grpcio/grpc_version.py
@@ -14,4 +14,4 @@
 
 # AUTO-GENERATED FROM `$REPO_ROOT/templates/src/python/grpcio/grpc_version.py.template`!!!
 
-VERSION = '1.21.0.dev0'
+VERSION = '1.21.0rc1'
diff --git a/src/python/grpcio_channelz/grpc_version.py b/src/python/grpcio_channelz/grpc_version.py
index d716b95..cbe46b7 100644
--- a/src/python/grpcio_channelz/grpc_version.py
+++ b/src/python/grpcio_channelz/grpc_version.py
@@ -14,4 +14,4 @@
 
 # AUTO-GENERATED FROM `$REPO_ROOT/templates/src/python/grpcio_channelz/grpc_version.py.template`!!!
 
-VERSION = '1.21.0.dev0'
+VERSION = '1.21.0rc1'
diff --git a/src/python/grpcio_health_checking/grpc_version.py b/src/python/grpcio_health_checking/grpc_version.py
index 2bb47aa..cfa2965 100644
--- a/src/python/grpcio_health_checking/grpc_version.py
+++ b/src/python/grpcio_health_checking/grpc_version.py
@@ -14,4 +14,4 @@
 
 # AUTO-GENERATED FROM `$REPO_ROOT/templates/src/python/grpcio_health_checking/grpc_version.py.template`!!!
 
-VERSION = '1.21.0.dev0'
+VERSION = '1.21.0rc1'
diff --git a/src/python/grpcio_reflection/grpc_version.py b/src/python/grpcio_reflection/grpc_version.py
index e1c4f3d..54261c7 100644
--- a/src/python/grpcio_reflection/grpc_version.py
+++ b/src/python/grpcio_reflection/grpc_version.py
@@ -14,4 +14,4 @@
 
 # AUTO-GENERATED FROM `$REPO_ROOT/templates/src/python/grpcio_reflection/grpc_version.py.template`!!!
 
-VERSION = '1.21.0.dev0'
+VERSION = '1.21.0rc1'
diff --git a/src/python/grpcio_status/grpc_version.py b/src/python/grpcio_status/grpc_version.py
index b484a7b..9a5e728 100644
--- a/src/python/grpcio_status/grpc_version.py
+++ b/src/python/grpcio_status/grpc_version.py
@@ -14,4 +14,4 @@
 
 # AUTO-GENERATED FROM `$REPO_ROOT/templates/src/python/grpcio_status/grpc_version.py.template`!!!
 
-VERSION = '1.21.0.dev0'
+VERSION = '1.21.0rc1'
diff --git a/src/python/grpcio_testing/grpc_version.py b/src/python/grpcio_testing/grpc_version.py
index 21981ee..7cd0ffa 100644
--- a/src/python/grpcio_testing/grpc_version.py
+++ b/src/python/grpcio_testing/grpc_version.py
@@ -14,4 +14,4 @@
 
 # AUTO-GENERATED FROM `$REPO_ROOT/templates/src/python/grpcio_testing/grpc_version.py.template`!!!
 
-VERSION = '1.21.0.dev0'
+VERSION = '1.21.0rc1'
diff --git a/src/python/grpcio_tests/grpc_version.py b/src/python/grpcio_tests/grpc_version.py
index 8ce4fdb..1a5e9f5 100644
--- a/src/python/grpcio_tests/grpc_version.py
+++ b/src/python/grpcio_tests/grpc_version.py
@@ -14,4 +14,4 @@
 
 # AUTO-GENERATED FROM `$REPO_ROOT/templates/src/python/grpcio_tests/grpc_version.py.template`!!!
 
-VERSION = '1.21.0.dev0'
+VERSION = '1.21.0rc1'
diff --git a/src/ruby/lib/grpc/version.rb b/src/ruby/lib/grpc/version.rb
index cca795b..30c4b3a 100644
--- a/src/ruby/lib/grpc/version.rb
+++ b/src/ruby/lib/grpc/version.rb
@@ -14,5 +14,5 @@
 
 # GRPC contains the General RPC module.
 module GRPC
-  VERSION = '1.21.0.dev'
+  VERSION = '1.21.0.pre1'
 end
diff --git a/src/ruby/tools/version.rb b/src/ruby/tools/version.rb
index 5604e21..19c79e4 100644
--- a/src/ruby/tools/version.rb
+++ b/src/ruby/tools/version.rb
@@ -14,6 +14,6 @@
 
 module GRPC
   module Tools
-    VERSION = '1.21.0.dev'
+    VERSION = '1.21.0.pre1'
   end
 end
diff --git a/tools/distrib/python/grpcio_tools/grpc_version.py b/tools/distrib/python/grpcio_tools/grpc_version.py
index 22d04c5..a91af1b 100644
--- a/tools/distrib/python/grpcio_tools/grpc_version.py
+++ b/tools/distrib/python/grpcio_tools/grpc_version.py
@@ -14,4 +14,4 @@
 
 # AUTO-GENERATED FROM `$REPO_ROOT/templates/tools/distrib/python/grpcio_tools/grpc_version.py.template`!!!
 
-VERSION = '1.21.0.dev0'
+VERSION = '1.21.0rc1'
diff --git a/tools/doxygen/Doxyfile.c++ b/tools/doxygen/Doxyfile.c++
index d587492..0a399e0 100644
--- a/tools/doxygen/Doxyfile.c++
+++ b/tools/doxygen/Doxyfile.c++
@@ -40,7 +40,7 @@
 # could be handy for archiving the generated documentation or if some version
 # control system is used.
 
-PROJECT_NUMBER         = 1.21.0-dev
+PROJECT_NUMBER         = 1.21.0-pre1
 
 # Using the PROJECT_BRIEF tag one can provide an optional one line description
 # for a project that appears at the top of each page and should give viewer a
diff --git a/tools/doxygen/Doxyfile.c++.internal b/tools/doxygen/Doxyfile.c++.internal
index ab0968b..e314e7e 100644
--- a/tools/doxygen/Doxyfile.c++.internal
+++ b/tools/doxygen/Doxyfile.c++.internal
@@ -40,7 +40,7 @@
 # could be handy for archiving the generated documentation or if some version
 # control system is used.
 
-PROJECT_NUMBER         = 1.21.0-dev
+PROJECT_NUMBER         = 1.21.0-pre1
 
 # Using the PROJECT_BRIEF tag one can provide an optional one line description
 # for a project that appears at the top of each page and should give viewer a