diff --git a/BUILD b/BUILD
index 693d95e17e147f8c67b47c56e418b3d7b34f592e..2bcd81a7c88f0e5a1e2d19947b4568fc04ee83f5 100644
--- a/BUILD
+++ b/BUILD
@@ -310,6 +310,7 @@ grpc_cc_library(
         "src/core/lib/profiling/stap_timers.c",
         "src/core/lib/support/arena.c",
         "src/core/lib/support/alloc.c",
+        "src/core/lib/support/atm.c",
         "src/core/lib/support/avl.c",
         "src/core/lib/support/backoff.c",
         "src/core/lib/support/cmdline.c",
@@ -698,6 +699,7 @@ grpc_cc_library(
         "src/core/ext/client_channel/resolver.c",
         "src/core/ext/client_channel/resolver_factory.c",
         "src/core/ext/client_channel/resolver_registry.c",
+        "src/core/ext/client_channel/retry_throttle.c",
         "src/core/ext/client_channel/subchannel.c",
         "src/core/ext/client_channel/subchannel_index.c",
         "src/core/ext/client_channel/uri_parser.c",
@@ -718,6 +720,7 @@ grpc_cc_library(
         "src/core/ext/client_channel/resolver.h",
         "src/core/ext/client_channel/resolver_factory.h",
         "src/core/ext/client_channel/resolver_registry.h",
+        "src/core/ext/client_channel/retry_throttle.h",
         "src/core/ext/client_channel/subchannel.h",
         "src/core/ext/client_channel/subchannel_index.h",
         "src/core/ext/client_channel/uri_parser.h",
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 851aeb8401b81aec61be8799fb0a8f2f203e55aa..90f600411be2a43780cea0e876c107ed58bb0e64 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -698,6 +698,7 @@ add_library(gpr
   src/core/lib/profiling/stap_timers.c
   src/core/lib/support/alloc.c
   src/core/lib/support/arena.c
+  src/core/lib/support/atm.c
   src/core/lib/support/avl.c
   src/core/lib/support/backoff.c
   src/core/lib/support/cmdline.c
@@ -1054,6 +1055,7 @@ add_library(grpc
   src/core/ext/client_channel/resolver.c
   src/core/ext/client_channel/resolver_factory.c
   src/core/ext/client_channel/resolver_registry.c
+  src/core/ext/client_channel/retry_throttle.c
   src/core/ext/client_channel/subchannel.c
   src/core/ext/client_channel/subchannel_index.c
   src/core/ext/client_channel/uri_parser.c
@@ -1339,6 +1341,7 @@ add_library(grpc_cronet
   src/core/ext/client_channel/resolver.c
   src/core/ext/client_channel/resolver_factory.c
   src/core/ext/client_channel/resolver_registry.c
+  src/core/ext/client_channel/retry_throttle.c
   src/core/ext/client_channel/subchannel.c
   src/core/ext/client_channel/subchannel_index.c
   src/core/ext/client_channel/uri_parser.c
@@ -1893,6 +1896,7 @@ add_library(grpc_unsecure
   src/core/ext/client_channel/resolver.c
   src/core/ext/client_channel/resolver_factory.c
   src/core/ext/client_channel/resolver_registry.c
+  src/core/ext/client_channel/retry_throttle.c
   src/core/ext/client_channel/subchannel.c
   src/core/ext/client_channel/subchannel_index.c
   src/core/ext/client_channel/uri_parser.c
@@ -2477,6 +2481,7 @@ add_library(grpc++_cronet
   src/core/ext/client_channel/resolver.c
   src/core/ext/client_channel/resolver_factory.c
   src/core/ext/client_channel/resolver_registry.c
+  src/core/ext/client_channel/retry_throttle.c
   src/core/ext/client_channel/subchannel.c
   src/core/ext/client_channel/subchannel_index.c
   src/core/ext/client_channel/uri_parser.c
diff --git a/Makefile b/Makefile
index d2104e973c8a93947bf186e534412644c74a8784..f00ea472bf2e9a5a144bec9ceaaa6c57f9ae386a 100644
--- a/Makefile
+++ b/Makefile
@@ -2609,6 +2609,7 @@ LIBGPR_SRC = \
     src/core/lib/profiling/stap_timers.c \
     src/core/lib/support/alloc.c \
     src/core/lib/support/arena.c \
+    src/core/lib/support/atm.c \
     src/core/lib/support/avl.c \
     src/core/lib/support/backoff.c \
     src/core/lib/support/cmdline.c \
@@ -2946,6 +2947,7 @@ LIBGRPC_SRC = \
     src/core/ext/client_channel/resolver.c \
     src/core/ext/client_channel/resolver_factory.c \
     src/core/ext/client_channel/resolver_registry.c \
+    src/core/ext/client_channel/retry_throttle.c \
     src/core/ext/client_channel/subchannel.c \
     src/core/ext/client_channel/subchannel_index.c \
     src/core/ext/client_channel/uri_parser.c \
@@ -3234,6 +3236,7 @@ LIBGRPC_CRONET_SRC = \
     src/core/ext/client_channel/resolver.c \
     src/core/ext/client_channel/resolver_factory.c \
     src/core/ext/client_channel/resolver_registry.c \
+    src/core/ext/client_channel/retry_throttle.c \
     src/core/ext/client_channel/subchannel.c \
     src/core/ext/client_channel/subchannel_index.c \
     src/core/ext/client_channel/uri_parser.c \
@@ -3771,6 +3774,7 @@ LIBGRPC_UNSECURE_SRC = \
     src/core/ext/client_channel/resolver.c \
     src/core/ext/client_channel/resolver_factory.c \
     src/core/ext/client_channel/resolver_registry.c \
+    src/core/ext/client_channel/retry_throttle.c \
     src/core/ext/client_channel/subchannel.c \
     src/core/ext/client_channel/subchannel_index.c \
     src/core/ext/client_channel/uri_parser.c \
@@ -4357,6 +4361,7 @@ LIBGRPC++_CRONET_SRC = \
     src/core/ext/client_channel/resolver.c \
     src/core/ext/client_channel/resolver_factory.c \
     src/core/ext/client_channel/resolver_registry.c \
+    src/core/ext/client_channel/retry_throttle.c \
     src/core/ext/client_channel/subchannel.c \
     src/core/ext/client_channel/subchannel_index.c \
     src/core/ext/client_channel/uri_parser.c \
diff --git a/binding.gyp b/binding.gyp
index f79374a44690982c839ef789df2ba23fc351bf26..3cb1de99a34a88a0405fdd6623202b3dd804e683 100644
--- a/binding.gyp
+++ b/binding.gyp
@@ -545,6 +545,7 @@
         'src/core/lib/profiling/stap_timers.c',
         'src/core/lib/support/alloc.c',
         'src/core/lib/support/arena.c',
+        'src/core/lib/support/atm.c',
         'src/core/lib/support/avl.c',
         'src/core/lib/support/backoff.c',
         'src/core/lib/support/cmdline.c',
@@ -800,6 +801,7 @@
         'src/core/ext/client_channel/resolver.c',
         'src/core/ext/client_channel/resolver_factory.c',
         'src/core/ext/client_channel/resolver_registry.c',
+        'src/core/ext/client_channel/retry_throttle.c',
         'src/core/ext/client_channel/subchannel.c',
         'src/core/ext/client_channel/subchannel_index.c',
         'src/core/ext/client_channel/uri_parser.c',
diff --git a/build.yaml b/build.yaml
index 80c9849ca4a197100b7cb77dd0aa8868fd503934..dc214428985cbf7d676c21519828b5b85251df5e 100644
--- a/build.yaml
+++ b/build.yaml
@@ -103,6 +103,7 @@ filegroups:
   - src/core/lib/profiling/stap_timers.c
   - src/core/lib/support/alloc.c
   - src/core/lib/support/arena.c
+  - src/core/lib/support/atm.c
   - src/core/lib/support/avl.c
   - src/core/lib/support/backoff.c
   - src/core/lib/support/cmdline.c
@@ -423,6 +424,7 @@ filegroups:
   - src/core/ext/client_channel/resolver.h
   - src/core/ext/client_channel/resolver_factory.h
   - src/core/ext/client_channel/resolver_registry.h
+  - src/core/ext/client_channel/retry_throttle.h
   - src/core/ext/client_channel/subchannel.h
   - src/core/ext/client_channel/subchannel_index.h
   - src/core/ext/client_channel/uri_parser.h
@@ -445,6 +447,7 @@ filegroups:
   - src/core/ext/client_channel/resolver.c
   - src/core/ext/client_channel/resolver_factory.c
   - src/core/ext/client_channel/resolver_registry.c
+  - src/core/ext/client_channel/retry_throttle.c
   - src/core/ext/client_channel/subchannel.c
   - src/core/ext/client_channel/subchannel_index.c
   - src/core/ext/client_channel/uri_parser.c
diff --git a/config.m4 b/config.m4
index 3194b26669078cb4e7b1a1e5ed6df3cf06e5b7a4..f1bd9d581a40fbeccbf1cb9c82fb4ccded1755dc 100644
--- a/config.m4
+++ b/config.m4
@@ -40,6 +40,7 @@ if test "$PHP_GRPC" != "no"; then
     src/core/lib/profiling/stap_timers.c \
     src/core/lib/support/alloc.c \
     src/core/lib/support/arena.c \
+    src/core/lib/support/atm.c \
     src/core/lib/support/avl.c \
     src/core/lib/support/backoff.c \
     src/core/lib/support/cmdline.c \
@@ -273,6 +274,7 @@ if test "$PHP_GRPC" != "no"; then
     src/core/ext/client_channel/resolver.c \
     src/core/ext/client_channel/resolver_factory.c \
     src/core/ext/client_channel/resolver_registry.c \
+    src/core/ext/client_channel/retry_throttle.c \
     src/core/ext/client_channel/subchannel.c \
     src/core/ext/client_channel/subchannel_index.c \
     src/core/ext/client_channel/uri_parser.c \
diff --git a/gRPC-Core.podspec b/gRPC-Core.podspec
index 2444ffa57abc1da39170a0b9a4b53f193786b9a0..899946a90aabdb0ea19fc2165777234959067b9a 100644
--- a/gRPC-Core.podspec
+++ b/gRPC-Core.podspec
@@ -213,6 +213,7 @@ Pod::Spec.new do |s|
                       'src/core/lib/profiling/stap_timers.c',
                       'src/core/lib/support/alloc.c',
                       'src/core/lib/support/arena.c',
+                      'src/core/lib/support/atm.c',
                       'src/core/lib/support/avl.c',
                       'src/core/lib/support/backoff.c',
                       'src/core/lib/support/cmdline.c',
@@ -421,6 +422,7 @@ Pod::Spec.new do |s|
                       'src/core/ext/client_channel/resolver.h',
                       'src/core/ext/client_channel/resolver_factory.h',
                       'src/core/ext/client_channel/resolver_registry.h',
+                      'src/core/ext/client_channel/retry_throttle.h',
                       'src/core/ext/client_channel/subchannel.h',
                       'src/core/ext/client_channel/subchannel_index.h',
                       'src/core/ext/client_channel/uri_parser.h',
@@ -643,6 +645,7 @@ Pod::Spec.new do |s|
                       'src/core/ext/client_channel/resolver.c',
                       'src/core/ext/client_channel/resolver_factory.c',
                       'src/core/ext/client_channel/resolver_registry.c',
+                      'src/core/ext/client_channel/retry_throttle.c',
                       'src/core/ext/client_channel/subchannel.c',
                       'src/core/ext/client_channel/subchannel_index.c',
                       'src/core/ext/client_channel/uri_parser.c',
@@ -861,6 +864,7 @@ Pod::Spec.new do |s|
                               'src/core/ext/client_channel/resolver.h',
                               'src/core/ext/client_channel/resolver_factory.h',
                               'src/core/ext/client_channel/resolver_registry.h',
+                              'src/core/ext/client_channel/retry_throttle.h',
                               'src/core/ext/client_channel/subchannel.h',
                               'src/core/ext/client_channel/subchannel_index.h',
                               'src/core/ext/client_channel/uri_parser.h',
diff --git a/grpc.gemspec b/grpc.gemspec
index 81e8733052b81bac1d2f3011c13b5a01e3bf808c..61345695acfd61b51ef7708c4244f4cee01dc16c 100755
--- a/grpc.gemspec
+++ b/grpc.gemspec
@@ -99,6 +99,7 @@ Gem::Specification.new do |s|
   s.files += %w( src/core/lib/profiling/stap_timers.c )
   s.files += %w( src/core/lib/support/alloc.c )
   s.files += %w( src/core/lib/support/arena.c )
+  s.files += %w( src/core/lib/support/atm.c )
   s.files += %w( src/core/lib/support/avl.c )
   s.files += %w( src/core/lib/support/backoff.c )
   s.files += %w( src/core/lib/support/cmdline.c )
@@ -338,6 +339,7 @@ Gem::Specification.new do |s|
   s.files += %w( src/core/ext/client_channel/resolver.h )
   s.files += %w( src/core/ext/client_channel/resolver_factory.h )
   s.files += %w( src/core/ext/client_channel/resolver_registry.h )
+  s.files += %w( src/core/ext/client_channel/retry_throttle.h )
   s.files += %w( src/core/ext/client_channel/subchannel.h )
   s.files += %w( src/core/ext/client_channel/subchannel_index.h )
   s.files += %w( src/core/ext/client_channel/uri_parser.h )
@@ -560,6 +562,7 @@ Gem::Specification.new do |s|
   s.files += %w( src/core/ext/client_channel/resolver.c )
   s.files += %w( src/core/ext/client_channel/resolver_factory.c )
   s.files += %w( src/core/ext/client_channel/resolver_registry.c )
+  s.files += %w( src/core/ext/client_channel/retry_throttle.c )
   s.files += %w( src/core/ext/client_channel/subchannel.c )
   s.files += %w( src/core/ext/client_channel/subchannel_index.c )
   s.files += %w( src/core/ext/client_channel/uri_parser.c )
diff --git a/include/grpc/impl/codegen/atm.h b/include/grpc/impl/codegen/atm.h
index ae00fb0f16989565732c1ef669d82ed547f4e6d4..4bd572d6d1841eadaf4c40eac0344ee67b534e68 100644
--- a/include/grpc/impl/codegen/atm.h
+++ b/include/grpc/impl/codegen/atm.h
@@ -92,4 +92,9 @@
 #error could not determine platform for atm
 #endif
 
+/** Adds \a delta to \a *value, clamping the result to the range specified
+    by \a min and \a max.  Returns the new value. */
+gpr_atm gpr_atm_no_barrier_clamped_add(gpr_atm *value, gpr_atm delta,
+                                       gpr_atm min, gpr_atm max);
+
 #endif /* GRPC_IMPL_CODEGEN_ATM_H */
diff --git a/package.xml b/package.xml
index c66706cfde7f207739a83fb9e8699cc59af2606c..c374f4a8eab7a56f9a62c0495cf5fbd52384dac2 100644
--- a/package.xml
+++ b/package.xml
@@ -108,6 +108,7 @@
     <file baseinstalldir="/" name="src/core/lib/profiling/stap_timers.c" role="src" />
     <file baseinstalldir="/" name="src/core/lib/support/alloc.c" role="src" />
     <file baseinstalldir="/" name="src/core/lib/support/arena.c" role="src" />
+    <file baseinstalldir="/" name="src/core/lib/support/atm.c" role="src" />
     <file baseinstalldir="/" name="src/core/lib/support/avl.c" role="src" />
     <file baseinstalldir="/" name="src/core/lib/support/backoff.c" role="src" />
     <file baseinstalldir="/" name="src/core/lib/support/cmdline.c" role="src" />
@@ -347,6 +348,7 @@
     <file baseinstalldir="/" name="src/core/ext/client_channel/resolver.h" role="src" />
     <file baseinstalldir="/" name="src/core/ext/client_channel/resolver_factory.h" role="src" />
     <file baseinstalldir="/" name="src/core/ext/client_channel/resolver_registry.h" role="src" />
+    <file baseinstalldir="/" name="src/core/ext/client_channel/retry_throttle.h" role="src" />
     <file baseinstalldir="/" name="src/core/ext/client_channel/subchannel.h" role="src" />
     <file baseinstalldir="/" name="src/core/ext/client_channel/subchannel_index.h" role="src" />
     <file baseinstalldir="/" name="src/core/ext/client_channel/uri_parser.h" role="src" />
@@ -569,6 +571,7 @@
     <file baseinstalldir="/" name="src/core/ext/client_channel/resolver.c" role="src" />
     <file baseinstalldir="/" name="src/core/ext/client_channel/resolver_factory.c" role="src" />
     <file baseinstalldir="/" name="src/core/ext/client_channel/resolver_registry.c" role="src" />
+    <file baseinstalldir="/" name="src/core/ext/client_channel/retry_throttle.c" role="src" />
     <file baseinstalldir="/" name="src/core/ext/client_channel/subchannel.c" role="src" />
     <file baseinstalldir="/" name="src/core/ext/client_channel/subchannel_index.c" role="src" />
     <file baseinstalldir="/" name="src/core/ext/client_channel/uri_parser.c" role="src" />
diff --git a/src/core/ext/client_channel/client_channel.c b/src/core/ext/client_channel/client_channel.c
index 960d00e815c3e5c9917a4cbf08db3f559882bac4..00c20913b0fe3bd119e1a7427809db889534af7c 100644
--- a/src/core/ext/client_channel/client_channel.c
+++ b/src/core/ext/client_channel/client_channel.c
@@ -47,6 +47,7 @@
 #include "src/core/ext/client_channel/lb_policy_registry.h"
 #include "src/core/ext/client_channel/proxy_mapper_registry.h"
 #include "src/core/ext/client_channel/resolver_registry.h"
+#include "src/core/ext/client_channel/retry_throttle.h"
 #include "src/core/ext/client_channel/subchannel.h"
 #include "src/core/lib/channel/channel_args.h"
 #include "src/core/lib/channel/connected_channel.h"
@@ -189,6 +190,8 @@ typedef struct client_channel_channel_data {
   grpc_combiner *combiner;
   /** currently active load balancer */
   grpc_lb_policy *lb_policy;
+  /** retry throttle data */
+  grpc_server_retry_throttle_data *retry_throttle_data;
   /** maps method names to method_parameters structs */
   grpc_slice_hash_table *method_params_table;
   /** incoming resolver result - set by resolver.next() */
@@ -284,6 +287,65 @@ static void watch_lb_policy_locked(grpc_exec_ctx *exec_ctx, channel_data *chand,
                                                &w->on_changed);
 }
 
+typedef struct {
+  char *server_name;
+  grpc_server_retry_throttle_data *retry_throttle_data;
+} service_config_parsing_state;
+
+static void parse_retry_throttle_params(const grpc_json *field, void *arg) {
+  service_config_parsing_state *parsing_state = arg;
+  if (strcmp(field->key, "retryThrottling") == 0) {
+    if (parsing_state->retry_throttle_data != NULL) return;  // Duplicate.
+    if (field->type != GRPC_JSON_OBJECT) return;
+    int max_milli_tokens = 0;
+    int milli_token_ratio = 0;
+    for (grpc_json *sub_field = field->child; sub_field != NULL;
+         sub_field = sub_field->next) {
+      if (sub_field->key == NULL) return;
+      if (strcmp(sub_field->key, "maxTokens") == 0) {
+        if (max_milli_tokens != 0) return;  // Duplicate.
+        if (sub_field->type != GRPC_JSON_NUMBER) return;
+        max_milli_tokens = gpr_parse_nonnegative_int(sub_field->value);
+        if (max_milli_tokens == -1) return;
+        max_milli_tokens *= 1000;
+      } else if (strcmp(sub_field->key, "tokenRatio") == 0) {
+        if (milli_token_ratio != 0) return;  // Duplicate.
+        if (sub_field->type != GRPC_JSON_NUMBER) return;
+        // We support up to 3 decimal digits.
+        size_t whole_len = strlen(sub_field->value);
+        uint32_t multiplier = 1;
+        uint32_t decimal_value = 0;
+        const char *decimal_point = strchr(sub_field->value, '.');
+        if (decimal_point != NULL) {
+          whole_len = (size_t)(decimal_point - sub_field->value);
+          multiplier = 1000;
+          size_t decimal_len = strlen(decimal_point + 1);
+          if (decimal_len > 3) decimal_len = 3;
+          if (!gpr_parse_bytes_to_uint32(decimal_point + 1, decimal_len,
+                                         &decimal_value)) {
+            return;
+          }
+          uint32_t decimal_multiplier = 1;
+          for (size_t i = 0; i < (3 - decimal_len); ++i) {
+            decimal_multiplier *= 10;
+          }
+          decimal_value *= decimal_multiplier;
+        }
+        uint32_t whole_value;
+        if (!gpr_parse_bytes_to_uint32(sub_field->value, whole_len,
+                                       &whole_value)) {
+          return;
+        }
+        milli_token_ratio = (int)((whole_value * multiplier) + decimal_value);
+        if (milli_token_ratio <= 0) return;
+      }
+    }
+    parsing_state->retry_throttle_data =
+        grpc_retry_throttle_map_get_data_for_server(
+            parsing_state->server_name, max_milli_tokens, milli_token_ratio);
+  }
+}
+
 static void on_resolver_result_changed_locked(grpc_exec_ctx *exec_ctx,
                                               void *arg, grpc_error *error) {
   channel_data *chand = arg;
@@ -295,6 +357,8 @@ static void on_resolver_result_changed_locked(grpc_exec_ctx *exec_ctx,
   bool exit_idle = false;
   grpc_error *state_error = GRPC_ERROR_CREATE("No load balancing policy");
   char *service_config_json = NULL;
+  service_config_parsing_state parsing_state;
+  memset(&parsing_state, 0, sizeof(parsing_state));
 
   if (chand->resolver_result != NULL) {
     // Find LB policy name.
@@ -355,6 +419,19 @@ static void on_resolver_result_changed_locked(grpc_exec_ctx *exec_ctx,
       grpc_service_config *service_config =
           grpc_service_config_create(service_config_json);
       if (service_config != NULL) {
+        channel_arg =
+            grpc_channel_args_find(chand->resolver_result, GRPC_ARG_SERVER_URI);
+        GPR_ASSERT(channel_arg != NULL);
+        GPR_ASSERT(channel_arg->type == GRPC_ARG_STRING);
+        grpc_uri *uri =
+            grpc_uri_parse(exec_ctx, channel_arg->value.string, true);
+        GPR_ASSERT(uri->path[0] != '\0');
+        parsing_state.server_name =
+            uri->path[0] == '/' ? uri->path + 1 : uri->path;
+        grpc_service_config_parse_global_params(
+            service_config, parse_retry_throttle_params, &parsing_state);
+        parsing_state.server_name = NULL;
+        grpc_uri_destroy(uri);
         method_params_table = grpc_service_config_create_method_config_table(
             exec_ctx, service_config, method_parameters_create_from_json,
             &method_parameters_vtable);
@@ -386,6 +463,11 @@ static void on_resolver_result_changed_locked(grpc_exec_ctx *exec_ctx,
     chand->info_service_config_json = service_config_json;
   }
   gpr_mu_unlock(&chand->info_mu);
+
+  if (chand->retry_throttle_data != NULL) {
+    grpc_server_retry_throttle_data_unref(chand->retry_throttle_data);
+  }
+  chand->retry_throttle_data = parsing_state.retry_throttle_data;
   if (chand->method_params_table != NULL) {
     grpc_slice_hash_table_unref(exec_ctx, chand->method_params_table);
   }
@@ -613,6 +695,9 @@ static void cc_destroy_channel_elem(grpc_exec_ctx *exec_ctx,
   }
   gpr_free(chand->info_lb_policy_name);
   gpr_free(chand->info_service_config_json);
+  if (chand->retry_throttle_data != NULL) {
+    grpc_server_retry_throttle_data_unref(chand->retry_throttle_data);
+  }
   if (chand->method_params_table != NULL) {
     grpc_slice_hash_table_unref(exec_ctx, chand->method_params_table);
   }
@@ -654,6 +739,7 @@ typedef struct client_channel_call_data {
   grpc_slice path;  // Request path.
   gpr_timespec call_start_time;
   gpr_timespec deadline;
+  grpc_server_retry_throttle_data *retry_throttle_data;
   method_parameters *method_params;
 
   grpc_error *cancel_error;
@@ -676,6 +762,9 @@ typedef struct client_channel_call_data {
   grpc_call_stack *owning_call;
 
   grpc_linked_mdelem lb_token_mdelem;
+
+  grpc_closure on_complete;
+  grpc_closure *original_on_complete;
 } call_data;
 
 grpc_subchannel_call *grpc_client_channel_get_subchannel_call(
@@ -728,7 +817,7 @@ static void retry_waiting_locked(grpc_exec_ctx *exec_ctx, call_data *calld) {
   gpr_free(ops);
 }
 
-// Sets calld->method_params.
+// Sets calld->method_params and calld->retry_throttle_data.
 // If the method params specify a timeout, populates
 // *per_method_deadline and returns true.
 static bool set_call_method_params_from_service_config_locked(
@@ -736,6 +825,10 @@ static bool set_call_method_params_from_service_config_locked(
     gpr_timespec *per_method_deadline) {
   channel_data *chand = elem->channel_data;
   call_data *calld = elem->call_data;
+  if (chand->retry_throttle_data != NULL) {
+    calld->retry_throttle_data =
+        grpc_server_retry_throttle_data_ref(chand->retry_throttle_data);
+  }
   if (chand->method_params_table != NULL) {
     calld->method_params = grpc_method_config_table_get(
         exec_ctx, chand->method_params_table, calld->path);
@@ -1056,6 +1149,26 @@ static void start_transport_stream_op_locked_inner(grpc_exec_ctx *exec_ctx,
   add_waiting_locked(calld, op);
 }
 
+static void on_complete(grpc_exec_ctx *exec_ctx, void *arg, grpc_error *error) {
+  grpc_call_element *elem = arg;
+  call_data *calld = elem->call_data;
+  if (calld->retry_throttle_data != NULL) {
+    if (error == GRPC_ERROR_NONE) {
+      grpc_server_retry_throttle_data_record_success(
+          calld->retry_throttle_data);
+    } else {
+      // TODO(roth): In a subsequent PR, check the return value here and
+      // decide whether or not to retry.  Note that we should only
+      // record failures whose statuses match the configured retryable
+      // or non-fatal status codes.
+      grpc_server_retry_throttle_data_record_failure(
+          calld->retry_throttle_data);
+    }
+  }
+  grpc_closure_run(exec_ctx, calld->original_on_complete,
+                   GRPC_ERROR_REF(error));
+}
+
 static void start_transport_stream_op_locked(grpc_exec_ctx *exec_ctx, void *arg,
                                              grpc_error *error_ignored) {
   GPR_TIMER_BEGIN("start_transport_stream_op_locked", 0);
@@ -1064,6 +1177,14 @@ static void start_transport_stream_op_locked(grpc_exec_ctx *exec_ctx, void *arg,
   grpc_call_element *elem = op->handler_private.args[0];
   call_data *calld = elem->call_data;
 
+  if (op->recv_trailing_metadata != NULL) {
+    GPR_ASSERT(op->on_complete != NULL);
+    calld->original_on_complete = op->on_complete;
+    grpc_closure_init(&calld->on_complete, on_complete, elem,
+                      grpc_schedule_on_exec_ctx);
+    op->on_complete = &calld->on_complete;
+  }
+
   start_transport_stream_op_locked_inner(exec_ctx, op, elem);
 
   GRPC_CALL_STACK_UNREF(exec_ctx, calld->owning_call,
diff --git a/src/core/ext/client_channel/client_channel_plugin.c b/src/core/ext/client_channel/client_channel_plugin.c
index 28d3b63f99d2dcf5e00468289c03f615aa3ed66e..f51277d0b29bffa3485d8311b12c93b268cf7293 100644
--- a/src/core/ext/client_channel/client_channel_plugin.c
+++ b/src/core/ext/client_channel/client_channel_plugin.c
@@ -43,6 +43,7 @@
 #include "src/core/ext/client_channel/lb_policy_registry.h"
 #include "src/core/ext/client_channel/proxy_mapper_registry.h"
 #include "src/core/ext/client_channel/resolver_registry.h"
+#include "src/core/ext/client_channel/retry_throttle.h"
 #include "src/core/ext/client_channel/subchannel_index.h"
 #include "src/core/lib/surface/channel_init.h"
 
@@ -82,6 +83,7 @@ static bool set_default_host_if_unset(grpc_exec_ctx *exec_ctx,
 void grpc_client_channel_init(void) {
   grpc_lb_policy_registry_init();
   grpc_resolver_registry_init();
+  grpc_retry_throttle_map_init();
   grpc_proxy_mapper_registry_init();
   grpc_register_http_proxy_mapper();
   grpc_subchannel_index_init();
@@ -96,6 +98,7 @@ void grpc_client_channel_shutdown(void) {
   grpc_subchannel_index_shutdown();
   grpc_channel_init_shutdown();
   grpc_proxy_mapper_registry_shutdown();
+  grpc_retry_throttle_map_shutdown();
   grpc_resolver_registry_shutdown();
   grpc_lb_policy_registry_shutdown();
 }
diff --git a/src/core/ext/client_channel/retry_throttle.c b/src/core/ext/client_channel/retry_throttle.c
new file mode 100644
index 0000000000000000000000000000000000000000..8926c3d7822d88efd28c3f2af44d6a6a86a07bba
--- /dev/null
+++ b/src/core/ext/client_channel/retry_throttle.c
@@ -0,0 +1,210 @@
+/*
+ *
+ * Copyright 2017, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#include "src/core/ext/client_channel/retry_throttle.h"
+
+#include <limits.h>
+#include <string.h>
+
+#include <grpc/support/alloc.h>
+#include <grpc/support/atm.h>
+#include <grpc/support/avl.h>
+#include <grpc/support/string_util.h>
+#include <grpc/support/sync.h>
+
+//
+// server_retry_throttle_data
+//
+
+struct grpc_server_retry_throttle_data {
+  gpr_refcount refs;
+  int max_milli_tokens;
+  int milli_token_ratio;
+  gpr_atm milli_tokens;
+  // A pointer to the replacement for this grpc_server_retry_throttle_data
+  // entry.  If non-NULL, then this entry is stale and must not be used.
+  // We hold a reference to the replacement.
+  gpr_atm replacement;
+};
+
+static void get_replacement_throttle_data_if_needed(
+    grpc_server_retry_throttle_data** throttle_data) {
+  while (true) {
+    grpc_server_retry_throttle_data* new_throttle_data =
+        (grpc_server_retry_throttle_data*)gpr_atm_acq_load(
+            &(*throttle_data)->replacement);
+    if (new_throttle_data == NULL) return;
+    *throttle_data = new_throttle_data;
+  }
+}
+
+bool grpc_server_retry_throttle_data_record_failure(
+    grpc_server_retry_throttle_data* throttle_data) {
+  // First, check if we are stale and need to be replaced.
+  get_replacement_throttle_data_if_needed(&throttle_data);
+  // We decrement milli_tokens by 1000 (1 token) for each failure.
+  const int new_value = (int)gpr_atm_no_barrier_clamped_add(
+      &throttle_data->milli_tokens, (gpr_atm)-1000, (gpr_atm)0,
+      (gpr_atm)throttle_data->max_milli_tokens);
+  // Retries are allowed as long as the new value is above the threshold
+  // (max_milli_tokens / 2).
+  return new_value > throttle_data->max_milli_tokens / 2;
+}
+
+void grpc_server_retry_throttle_data_record_success(
+    grpc_server_retry_throttle_data* throttle_data) {
+  // First, check if we are stale and need to be replaced.
+  get_replacement_throttle_data_if_needed(&throttle_data);
+  // We increment milli_tokens by milli_token_ratio for each success.
+  gpr_atm_no_barrier_clamped_add(
+      &throttle_data->milli_tokens, (gpr_atm)throttle_data->milli_token_ratio,
+      (gpr_atm)0, (gpr_atm)throttle_data->max_milli_tokens);
+}
+
+grpc_server_retry_throttle_data* grpc_server_retry_throttle_data_ref(
+    grpc_server_retry_throttle_data* throttle_data) {
+  gpr_ref(&throttle_data->refs);
+  return throttle_data;
+}
+
+void grpc_server_retry_throttle_data_unref(
+    grpc_server_retry_throttle_data* throttle_data) {
+  if (gpr_unref(&throttle_data->refs)) {
+    grpc_server_retry_throttle_data* replacement =
+        (grpc_server_retry_throttle_data*)gpr_atm_acq_load(
+            &throttle_data->replacement);
+    if (replacement != NULL) {
+      grpc_server_retry_throttle_data_unref(replacement);
+    }
+    gpr_free(throttle_data);
+  }
+}
+
+static grpc_server_retry_throttle_data* grpc_server_retry_throttle_data_create(
+    int max_milli_tokens, int milli_token_ratio,
+    grpc_server_retry_throttle_data* old_throttle_data) {
+  grpc_server_retry_throttle_data* throttle_data =
+      gpr_malloc(sizeof(*throttle_data));
+  memset(throttle_data, 0, sizeof(*throttle_data));
+  gpr_ref_init(&throttle_data->refs, 1);
+  throttle_data->max_milli_tokens = max_milli_tokens;
+  throttle_data->milli_token_ratio = milli_token_ratio;
+  int initial_milli_tokens = max_milli_tokens;
+  // If there was a pre-existing entry for this server name, initialize
+  // the token count by scaling proportionately to the old data.  This
+  // ensures that if we're already throttling retries on the old scale,
+  // we will start out doing the same thing on the new one.
+  if (old_throttle_data != NULL) {
+    double token_fraction =
+        (int)gpr_atm_acq_load(&old_throttle_data->milli_tokens) /
+        (double)old_throttle_data->max_milli_tokens;
+    initial_milli_tokens = (int)(token_fraction * max_milli_tokens);
+  }
+  gpr_atm_rel_store(&throttle_data->milli_tokens,
+                    (gpr_atm)initial_milli_tokens);
+  // If there was a pre-existing entry, mark it as stale and give it a
+  // pointer to the new entry, which is its replacement.
+  if (old_throttle_data != NULL) {
+    grpc_server_retry_throttle_data_ref(throttle_data);
+    gpr_atm_rel_store(&old_throttle_data->replacement, (gpr_atm)throttle_data);
+  }
+  return throttle_data;
+}
+
+//
+// avl vtable for string -> server_retry_throttle_data map
+//
+
+static void* copy_server_name(void* key) { return gpr_strdup(key); }
+
+static long compare_server_name(void* key1, void* key2) {
+  return strcmp(key1, key2);
+}
+
+static void destroy_server_retry_throttle_data(void* value) {
+  grpc_server_retry_throttle_data* throttle_data = value;
+  grpc_server_retry_throttle_data_unref(throttle_data);
+}
+
+static void* copy_server_retry_throttle_data(void* value) {
+  grpc_server_retry_throttle_data* throttle_data = value;
+  return grpc_server_retry_throttle_data_ref(throttle_data);
+}
+
+static const gpr_avl_vtable avl_vtable = {
+    gpr_free /* destroy_key */, copy_server_name, compare_server_name,
+    destroy_server_retry_throttle_data, copy_server_retry_throttle_data};
+
+//
+// server_retry_throttle_map
+//
+
+static gpr_mu g_mu;
+static gpr_avl g_avl;
+
+void grpc_retry_throttle_map_init() {
+  gpr_mu_init(&g_mu);
+  g_avl = gpr_avl_create(&avl_vtable);
+}
+
+void grpc_retry_throttle_map_shutdown() {
+  gpr_mu_destroy(&g_mu);
+  gpr_avl_unref(g_avl);
+}
+
+grpc_server_retry_throttle_data* grpc_retry_throttle_map_get_data_for_server(
+    const char* server_name, int max_milli_tokens, int milli_token_ratio) {
+  gpr_mu_lock(&g_mu);
+  grpc_server_retry_throttle_data* throttle_data =
+      gpr_avl_get(g_avl, (char*)server_name);
+  if (throttle_data == NULL) {
+    // Entry not found.  Create a new one.
+    throttle_data = grpc_server_retry_throttle_data_create(
+        max_milli_tokens, milli_token_ratio, NULL);
+    g_avl = gpr_avl_add(g_avl, (char*)server_name, throttle_data);
+  } else {
+    if (throttle_data->max_milli_tokens != max_milli_tokens ||
+        throttle_data->milli_token_ratio != milli_token_ratio) {
+      // Entry found but with old parameters.  Create a new one based on
+      // the original one.
+      throttle_data = grpc_server_retry_throttle_data_create(
+          max_milli_tokens, milli_token_ratio, throttle_data);
+      g_avl = gpr_avl_add(g_avl, (char*)server_name, throttle_data);
+    } else {
+      // Entry found.  Increase refcount.
+      grpc_server_retry_throttle_data_ref(throttle_data);
+    }
+  }
+  gpr_mu_unlock(&g_mu);
+  return throttle_data;
+}
diff --git a/src/core/ext/client_channel/retry_throttle.h b/src/core/ext/client_channel/retry_throttle.h
new file mode 100644
index 0000000000000000000000000000000000000000..f9971faf6515cbd69b20b647e6700aa963e4fbf1
--- /dev/null
+++ b/src/core/ext/client_channel/retry_throttle.h
@@ -0,0 +1,65 @@
+/*
+ *
+ * Copyright 2017, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#ifndef GRPC_CORE_EXT_CLIENT_CHANNEL_RETRY_THROTTLE_H
+#define GRPC_CORE_EXT_CLIENT_CHANNEL_RETRY_THROTTLE_H
+
+#include <stdbool.h>
+
+/// Tracks retry throttling data for an individual server name.
+typedef struct grpc_server_retry_throttle_data grpc_server_retry_throttle_data;
+
+/// Records a failure.  Returns true if it's okay to send a retry.
+bool grpc_server_retry_throttle_data_record_failure(
+    grpc_server_retry_throttle_data* throttle_data);
+/// Records a success.
+void grpc_server_retry_throttle_data_record_success(
+    grpc_server_retry_throttle_data* throttle_data);
+
+grpc_server_retry_throttle_data* grpc_server_retry_throttle_data_ref(
+    grpc_server_retry_throttle_data* throttle_data);
+void grpc_server_retry_throttle_data_unref(
+    grpc_server_retry_throttle_data* throttle_data);
+
+/// Initializes global map of failure data for each server name.
+void grpc_retry_throttle_map_init();
+/// Shuts down global map of failure data for each server name.
+void grpc_retry_throttle_map_shutdown();
+
+/// Returns a reference to the failure data for \a server_name, creating
+/// a new entry if needed.
+/// Caller must eventually unref via \a grpc_server_retry_throttle_data_unref().
+grpc_server_retry_throttle_data* grpc_retry_throttle_map_get_data_for_server(
+    const char* server_name, int max_milli_tokens, int milli_token_ratio);
+
+#endif /* GRPC_CORE_EXT_CLIENT_CHANNEL_RETRY_THROTTLE_H */
diff --git a/src/core/ext/transport/chttp2/transport/chttp2_transport.c b/src/core/ext/transport/chttp2/transport/chttp2_transport.c
index 082078c72f0a017bf446399b335c8e0c61b2b71d..89659e7464f5859e4b94fa870d68976eceffd2af 100644
--- a/src/core/ext/transport/chttp2/transport/chttp2_transport.c
+++ b/src/core/ext/transport/chttp2/transport/chttp2_transport.c
@@ -1765,6 +1765,7 @@ static void close_from_api(grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t,
                            grpc_chttp2_stream *s, grpc_error *error) {
   grpc_slice hdr;
   grpc_slice status_hdr;
+  grpc_slice http_status_hdr;
   grpc_slice message_pfx;
   uint8_t *p;
   uint32_t len = 0;
@@ -1780,6 +1781,26 @@ static void close_from_api(grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t,
      It's complicated by the fact that our send machinery would be dead by
      the time we got around to sending this, so instead we ignore HPACK
      compression and just write the uncompressed bytes onto the wire. */
+  if (!s->sent_initial_metadata) {
+    http_status_hdr = grpc_slice_malloc(13);
+    p = GRPC_SLICE_START_PTR(http_status_hdr);
+    *p++ = 0x00;
+    *p++ = 7;
+    *p++ = ':';
+    *p++ = 's';
+    *p++ = 't';
+    *p++ = 'a';
+    *p++ = 't';
+    *p++ = 'u';
+    *p++ = 's';
+    *p++ = 3;
+    *p++ = '2';
+    *p++ = '0';
+    *p++ = '0';
+    GPR_ASSERT(p == GRPC_SLICE_END_PTR(http_status_hdr));
+    len += (uint32_t)GRPC_SLICE_LENGTH(http_status_hdr);
+  }
+
   status_hdr = grpc_slice_malloc(15 + (grpc_status >= 10));
   p = GRPC_SLICE_START_PTR(status_hdr);
   *p++ = 0x00; /* literal header, not indexed */
@@ -1847,6 +1868,9 @@ static void close_from_api(grpc_exec_ctx *exec_ctx, grpc_chttp2_transport *t,
   GPR_ASSERT(p == GRPC_SLICE_END_PTR(hdr));
 
   grpc_slice_buffer_add(&t->qbuf, hdr);
+  if (!s->sent_initial_metadata) {
+    grpc_slice_buffer_add(&t->qbuf, http_status_hdr);
+  }
   grpc_slice_buffer_add(&t->qbuf, status_hdr);
   if (msg != NULL) {
     grpc_slice_buffer_add(&t->qbuf, message_pfx);
diff --git a/src/core/lib/support/atm.c b/src/core/lib/support/atm.c
new file mode 100644
index 0000000000000000000000000000000000000000..06e8432caf887d6cb9bc06084dccab6c484c84cd
--- /dev/null
+++ b/src/core/lib/support/atm.c
@@ -0,0 +1,47 @@
+/*
+ *
+ * Copyright 2017, Google Inc.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ */
+
+#include <grpc/support/atm.h>
+#include <grpc/support/useful.h>
+
+gpr_atm gpr_atm_no_barrier_clamped_add(gpr_atm *value, gpr_atm delta,
+                                       gpr_atm min, gpr_atm max) {
+  gpr_atm current;
+  gpr_atm new;
+  do {
+    current = gpr_atm_no_barrier_load(value);
+    new = GPR_CLAMP(current + delta, min, max);
+    if (new == current) break;
+  } while (!gpr_atm_no_barrier_cas(value, current, new));
+  return new;
+}
diff --git a/src/core/lib/transport/service_config.c b/src/core/lib/transport/service_config.c
index 12da2a88feb9537ace387c80d8be1fa13157cb75..1195f75044a4a64ac04c4fa2a79f6a9a2808f38c 100644
--- a/src/core/lib/transport/service_config.c
+++ b/src/core/lib/transport/service_config.c
@@ -93,6 +93,18 @@ void grpc_service_config_destroy(grpc_service_config* service_config) {
   gpr_free(service_config);
 }
 
+void grpc_service_config_parse_global_params(
+    const grpc_service_config* service_config,
+    void (*process_json)(const grpc_json* json, void* arg), void* arg) {
+  const grpc_json* json = service_config->json_tree;
+  if (json->type != GRPC_JSON_OBJECT || json->key != NULL) return;
+  for (grpc_json* field = json->child; field != NULL; field = field->next) {
+    if (field->key == NULL) return;
+    if (strcmp(field->key, "methodConfig") == 0) continue;
+    process_json(field, arg);
+  }
+}
+
 const char* grpc_service_config_get_lb_policy_name(
     const grpc_service_config* service_config) {
   const grpc_json* json = service_config->json_tree;
diff --git a/src/core/lib/transport/service_config.h b/src/core/lib/transport/service_config.h
index cd739a593c27f939d2d7963ecee4d84e9619aa65..ebfc59b5347f057e775889c6c9d5be2b1a44f45b 100644
--- a/src/core/lib/transport/service_config.h
+++ b/src/core/lib/transport/service_config.h
@@ -42,6 +42,12 @@ typedef struct grpc_service_config grpc_service_config;
 grpc_service_config* grpc_service_config_create(const char* json_string);
 void grpc_service_config_destroy(grpc_service_config* service_config);
 
+/// Invokes \a process_json() for each global parameter in the service
+/// config.  \a arg is passed as the second argument to \a process_json().
+void grpc_service_config_parse_global_params(
+    const grpc_service_config* service_config,
+    void (*process_json)(const grpc_json* json, void* arg), void* arg);
+
 /// Gets the LB policy name from \a service_config.
 /// Returns NULL if no LB policy name was specified.
 /// Caller does NOT take ownership.
diff --git a/src/python/grpcio/grpc_core_dependencies.py b/src/python/grpcio/grpc_core_dependencies.py
index 5fc748483a7a2197ca78f326b37b71c4321e9f4e..8edab1b759dff095c6938b1d6f608f357a048dbe 100644
--- a/src/python/grpcio/grpc_core_dependencies.py
+++ b/src/python/grpcio/grpc_core_dependencies.py
@@ -34,6 +34,7 @@ CORE_SOURCE_FILES = [
   'src/core/lib/profiling/stap_timers.c',
   'src/core/lib/support/alloc.c',
   'src/core/lib/support/arena.c',
+  'src/core/lib/support/atm.c',
   'src/core/lib/support/avl.c',
   'src/core/lib/support/backoff.c',
   'src/core/lib/support/cmdline.c',
@@ -267,6 +268,7 @@ CORE_SOURCE_FILES = [
   'src/core/ext/client_channel/resolver.c',
   'src/core/ext/client_channel/resolver_factory.c',
   'src/core/ext/client_channel/resolver_registry.c',
+  'src/core/ext/client_channel/retry_throttle.c',
   'src/core/ext/client_channel/subchannel.c',
   'src/core/ext/client_channel/subchannel_index.c',
   'src/core/ext/client_channel/uri_parser.c',
diff --git a/tools/doxygen/Doxyfile.core.internal b/tools/doxygen/Doxyfile.core.internal
index 89223630980181863a70c488c0f0bb2ba6fd425b..eb1c42debb869995d6405c8653d7fbc3a274b93b 100644
--- a/tools/doxygen/Doxyfile.core.internal
+++ b/tools/doxygen/Doxyfile.core.internal
@@ -929,6 +929,8 @@ src/core/ext/client_channel/resolver_factory.c \
 src/core/ext/client_channel/resolver_factory.h \
 src/core/ext/client_channel/resolver_registry.c \
 src/core/ext/client_channel/resolver_registry.h \
+src/core/ext/client_channel/retry_throttle.c \
+src/core/ext/client_channel/retry_throttle.h \
 src/core/ext/client_channel/subchannel.c \
 src/core/ext/client_channel/subchannel.h \
 src/core/ext/client_channel/subchannel_index.c \
@@ -1235,6 +1237,7 @@ src/core/lib/slice/slice_string_helpers.h \
 src/core/lib/support/alloc.c \
 src/core/lib/support/arena.c \
 src/core/lib/support/arena.h \
+src/core/lib/support/atm.c \
 src/core/lib/support/avl.c \
 src/core/lib/support/backoff.c \
 src/core/lib/support/backoff.h \
diff --git a/tools/run_tests/generated/sources_and_headers.json b/tools/run_tests/generated/sources_and_headers.json
index 9160b0d9d6720b704f6f3764a983694b14e14da2..940f29508711df8d87a44bef38a54432ce127815 100644
--- a/tools/run_tests/generated/sources_and_headers.json
+++ b/tools/run_tests/generated/sources_and_headers.json
@@ -7350,6 +7350,7 @@
       "src/core/lib/support/alloc.c", 
       "src/core/lib/support/arena.c", 
       "src/core/lib/support/arena.h", 
+      "src/core/lib/support/atm.c", 
       "src/core/lib/support/avl.c", 
       "src/core/lib/support/backoff.c", 
       "src/core/lib/support/backoff.h", 
@@ -7834,6 +7835,7 @@
       "src/core/ext/client_channel/resolver.h", 
       "src/core/ext/client_channel/resolver_factory.h", 
       "src/core/ext/client_channel/resolver_registry.h", 
+      "src/core/ext/client_channel/retry_throttle.h", 
       "src/core/ext/client_channel/subchannel.h", 
       "src/core/ext/client_channel/subchannel_index.h", 
       "src/core/ext/client_channel/uri_parser.h"
@@ -7875,6 +7877,8 @@
       "src/core/ext/client_channel/resolver_factory.h", 
       "src/core/ext/client_channel/resolver_registry.c", 
       "src/core/ext/client_channel/resolver_registry.h", 
+      "src/core/ext/client_channel/retry_throttle.c", 
+      "src/core/ext/client_channel/retry_throttle.h", 
       "src/core/ext/client_channel/subchannel.c", 
       "src/core/ext/client_channel/subchannel.h", 
       "src/core/ext/client_channel/subchannel_index.c", 
diff --git a/tools/run_tests/generated/tests.json b/tools/run_tests/generated/tests.json
index 1af05162b4f6495a596cdcad32c81836d7d8f63c..8c708f09ee3c2c76867839c8462ddb940b4fe598 100644
--- a/tools/run_tests/generated/tests.json
+++ b/tools/run_tests/generated/tests.json
@@ -117505,6 +117505,7 @@
     "language": "c", 
     "name": "hpack_parser_fuzzer_test_one_entry", 
     "platforms": [
+      "mac", 
       "linux"
     ], 
     "uses_polling": false
diff --git a/vsprojects/vcxproj/gpr/gpr.vcxproj b/vsprojects/vcxproj/gpr/gpr.vcxproj
index 1b37ace69abdd606bf3b3ba61477c8b2d696f220..32dedee55d3047ca865c6762759dac46713c3d52 100644
--- a/vsprojects/vcxproj/gpr/gpr.vcxproj
+++ b/vsprojects/vcxproj/gpr/gpr.vcxproj
@@ -211,6 +211,8 @@
     </ClCompile>
     <ClCompile Include="$(SolutionDir)\..\src\core\lib\support\arena.c">
     </ClCompile>
+    <ClCompile Include="$(SolutionDir)\..\src\core\lib\support\atm.c">
+    </ClCompile>
     <ClCompile Include="$(SolutionDir)\..\src\core\lib\support\avl.c">
     </ClCompile>
     <ClCompile Include="$(SolutionDir)\..\src\core\lib\support\backoff.c">
diff --git a/vsprojects/vcxproj/gpr/gpr.vcxproj.filters b/vsprojects/vcxproj/gpr/gpr.vcxproj.filters
index fafd54cdf9315ae8d5f1aa2d7fe6180715206d09..94699c8ff8c6d9efba55aeb785a7ed153be1f4b7 100644
--- a/vsprojects/vcxproj/gpr/gpr.vcxproj.filters
+++ b/vsprojects/vcxproj/gpr/gpr.vcxproj.filters
@@ -13,6 +13,9 @@
     <ClCompile Include="$(SolutionDir)\..\src\core\lib\support\arena.c">
       <Filter>src\core\lib\support</Filter>
     </ClCompile>
+    <ClCompile Include="$(SolutionDir)\..\src\core\lib\support\atm.c">
+      <Filter>src\core\lib\support</Filter>
+    </ClCompile>
     <ClCompile Include="$(SolutionDir)\..\src\core\lib\support\avl.c">
       <Filter>src\core\lib\support</Filter>
     </ClCompile>
diff --git a/vsprojects/vcxproj/grpc/grpc.vcxproj b/vsprojects/vcxproj/grpc/grpc.vcxproj
index 5e3b027663d6da1373066ab3f58436942985caea..d4d59c0db72f29b7a3c8a096d0dacf52d16168b0 100644
--- a/vsprojects/vcxproj/grpc/grpc.vcxproj
+++ b/vsprojects/vcxproj/grpc/grpc.vcxproj
@@ -467,6 +467,7 @@
     <ClInclude Include="$(SolutionDir)\..\src\core\ext\client_channel\resolver.h" />
     <ClInclude Include="$(SolutionDir)\..\src\core\ext\client_channel\resolver_factory.h" />
     <ClInclude Include="$(SolutionDir)\..\src\core\ext\client_channel\resolver_registry.h" />
+    <ClInclude Include="$(SolutionDir)\..\src\core\ext\client_channel\retry_throttle.h" />
     <ClInclude Include="$(SolutionDir)\..\src\core\ext\client_channel\subchannel.h" />
     <ClInclude Include="$(SolutionDir)\..\src\core\ext\client_channel\subchannel_index.h" />
     <ClInclude Include="$(SolutionDir)\..\src\core\ext\client_channel\uri_parser.h" />
@@ -883,6 +884,8 @@
     </ClCompile>
     <ClCompile Include="$(SolutionDir)\..\src\core\ext\client_channel\resolver_registry.c">
     </ClCompile>
+    <ClCompile Include="$(SolutionDir)\..\src\core\ext\client_channel\retry_throttle.c">
+    </ClCompile>
     <ClCompile Include="$(SolutionDir)\..\src\core\ext\client_channel\subchannel.c">
     </ClCompile>
     <ClCompile Include="$(SolutionDir)\..\src\core\ext\client_channel\subchannel_index.c">
diff --git a/vsprojects/vcxproj/grpc/grpc.vcxproj.filters b/vsprojects/vcxproj/grpc/grpc.vcxproj.filters
index d75ca766c0d251849ce062d9bb62751bc0d5fa1f..45f1944c2d823758ba4cfa1fb53112dc65eac616 100644
--- a/vsprojects/vcxproj/grpc/grpc.vcxproj.filters
+++ b/vsprojects/vcxproj/grpc/grpc.vcxproj.filters
@@ -577,6 +577,9 @@
     <ClCompile Include="$(SolutionDir)\..\src\core\ext\client_channel\resolver_registry.c">
       <Filter>src\core\ext\client_channel</Filter>
     </ClCompile>
+    <ClCompile Include="$(SolutionDir)\..\src\core\ext\client_channel\retry_throttle.c">
+      <Filter>src\core\ext\client_channel</Filter>
+    </ClCompile>
     <ClCompile Include="$(SolutionDir)\..\src\core\ext\client_channel\subchannel.c">
       <Filter>src\core\ext\client_channel</Filter>
     </ClCompile>
@@ -1283,6 +1286,9 @@
     <ClInclude Include="$(SolutionDir)\..\src\core\ext\client_channel\resolver_registry.h">
       <Filter>src\core\ext\client_channel</Filter>
     </ClInclude>
+    <ClInclude Include="$(SolutionDir)\..\src\core\ext\client_channel\retry_throttle.h">
+      <Filter>src\core\ext\client_channel</Filter>
+    </ClInclude>
     <ClInclude Include="$(SolutionDir)\..\src\core\ext\client_channel\subchannel.h">
       <Filter>src\core\ext\client_channel</Filter>
     </ClInclude>
diff --git a/vsprojects/vcxproj/grpc_unsecure/grpc_unsecure.vcxproj b/vsprojects/vcxproj/grpc_unsecure/grpc_unsecure.vcxproj
index 11ac8bd4b2baf5e8f01ac5ffae485e839f3c3cff..cba1dfac95a2f2f91401bdde9e250c83579dd299 100644
--- a/vsprojects/vcxproj/grpc_unsecure/grpc_unsecure.vcxproj
+++ b/vsprojects/vcxproj/grpc_unsecure/grpc_unsecure.vcxproj
@@ -433,6 +433,7 @@
     <ClInclude Include="$(SolutionDir)\..\src\core\ext\client_channel\resolver.h" />
     <ClInclude Include="$(SolutionDir)\..\src\core\ext\client_channel\resolver_factory.h" />
     <ClInclude Include="$(SolutionDir)\..\src\core\ext\client_channel\resolver_registry.h" />
+    <ClInclude Include="$(SolutionDir)\..\src\core\ext\client_channel\retry_throttle.h" />
     <ClInclude Include="$(SolutionDir)\..\src\core\ext\client_channel\subchannel.h" />
     <ClInclude Include="$(SolutionDir)\..\src\core\ext\client_channel\subchannel_index.h" />
     <ClInclude Include="$(SolutionDir)\..\src\core\ext\client_channel\uri_parser.h" />
@@ -800,6 +801,8 @@
     </ClCompile>
     <ClCompile Include="$(SolutionDir)\..\src\core\ext\client_channel\resolver_registry.c">
     </ClCompile>
+    <ClCompile Include="$(SolutionDir)\..\src\core\ext\client_channel\retry_throttle.c">
+    </ClCompile>
     <ClCompile Include="$(SolutionDir)\..\src\core\ext\client_channel\subchannel.c">
     </ClCompile>
     <ClCompile Include="$(SolutionDir)\..\src\core\ext\client_channel\subchannel_index.c">
diff --git a/vsprojects/vcxproj/grpc_unsecure/grpc_unsecure.vcxproj.filters b/vsprojects/vcxproj/grpc_unsecure/grpc_unsecure.vcxproj.filters
index 414e2a50b89f003fcdc540bfcb7aff383be4e495..1bf5374e022c21184f74edcc723bbfdef714389f 100644
--- a/vsprojects/vcxproj/grpc_unsecure/grpc_unsecure.vcxproj.filters
+++ b/vsprojects/vcxproj/grpc_unsecure/grpc_unsecure.vcxproj.filters
@@ -505,6 +505,9 @@
     <ClCompile Include="$(SolutionDir)\..\src\core\ext\client_channel\resolver_registry.c">
       <Filter>src\core\ext\client_channel</Filter>
     </ClCompile>
+    <ClCompile Include="$(SolutionDir)\..\src\core\ext\client_channel\retry_throttle.c">
+      <Filter>src\core\ext\client_channel</Filter>
+    </ClCompile>
     <ClCompile Include="$(SolutionDir)\..\src\core\ext\client_channel\subchannel.c">
       <Filter>src\core\ext\client_channel</Filter>
     </ClCompile>
@@ -1121,6 +1124,9 @@
     <ClInclude Include="$(SolutionDir)\..\src\core\ext\client_channel\resolver_registry.h">
       <Filter>src\core\ext\client_channel</Filter>
     </ClInclude>
+    <ClInclude Include="$(SolutionDir)\..\src\core\ext\client_channel\retry_throttle.h">
+      <Filter>src\core\ext\client_channel</Filter>
+    </ClInclude>
     <ClInclude Include="$(SolutionDir)\..\src\core\ext\client_channel\subchannel.h">
       <Filter>src\core\ext\client_channel</Filter>
     </ClInclude>