diff --git a/mysql-test/r/fast_prefix_index_fetch_innodb.result b/mysql-test/r/fast_prefix_index_fetch_innodb.result
new file mode 100644
index 00000000000..92af85f7fdb
--- /dev/null
+++ b/mysql-test/r/fast_prefix_index_fetch_innodb.result
@@ -0,0 +1,102 @@
+drop table if exists prefixinno;
+set global innodb_prefix_index_cluster_optimization = ON;
+show variables like 'innodb_prefix_index_cluster_optimization';
+Variable_name	Value
+innodb_prefix_index_cluster_optimization	ON
+# Create a table with a large varchar field that we index the prefix
+# of and ensure we only trigger cluster lookups when we expect it.
+create table prefixinno (
+id int not null,
+fake_id int not null,
+bigfield varchar(4096),
+primary key(id),
+index bigfield_idx (bigfield(32)),
+index fake_id_bigfield_prefix (fake_id, bigfield(32))
+) engine=innodb;
+insert into prefixinno values (1, 1001, repeat('a', 1)),
+(8, 1008, repeat('b', 8)),
+(24, 1024, repeat('c', 24)),
+(31, 1031, repeat('d', 31)),
+(32, 1032, repeat('x', 32)),
+(33, 1033, repeat('y', 33)),
+(128, 1128, repeat('z', 128));
+select * from prefixinno;
+id	fake_id	bigfield
+1	1001	a
+8	1008	bbbbbbbb
+24	1024	cccccccccccccccccccccccc
+31	1031	ddddddddddddddddddddddddddddddd
+32	1032	xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
+33	1033	yyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy
+128	1128	zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz
+# Baseline sanity check: 0, 0.
+no-op query
+no-op query
+cluster_lookups_matched
+1
+cluster_lookups_avoided_matched
+1
+# Eligible for optimization.
+id	bigfield
+31	ddddddddddddddddddddddddddddddd
+cluster_lookups_matched
+1
+cluster_lookups_avoided_matched
+1
+# Eligible for optimization, access via fake_id only.
+id	bigfield
+31	ddddddddddddddddddddddddddddddd
+cluster_lookups_matched
+1
+cluster_lookups_avoided_matched
+1
+# Not eligible for optimization, access via fake_id of big row.
+id	bigfield
+33	yyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy
+cluster_lookups_matched
+1
+cluster_lookups_avoided_matched
+1
+# Not eligible for optimization.
+id	bigfield
+32	xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
+cluster_lookups_matched
+1
+cluster_lookups_avoided_matched
+1
+# Not eligible for optimization.
+id	bigfield
+33	yyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy
+cluster_lookups_matched
+1
+cluster_lookups_avoided_matched
+1
+# Eligible, should not increment lookup counter.
+id	bigfield
+8	bbbbbbbb
+cluster_lookups_matched
+1
+cluster_lookups_avoided_matched
+1
+# Eligible, should not increment lookup counter.
+id	bigfield
+24	cccccccccccccccccccccccc
+cluster_lookups_matched
+1
+cluster_lookups_avoided_matched
+1
+# Should increment lookup counter.
+id	bigfield
+128	zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz
+cluster_lookups_matched
+1
+cluster_lookups_avoided_matched
+1
+# Disable optimization, confirm we still increment counter.
+id	bigfield
+33	yyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy
+cluster_lookups_matched
+1
+cluster_lookups_avoided_matched
+1
+# make test suite happy by cleaning up our mess
diff --git a/mysql-test/suite/sys_vars/r/innodb_monitor_disable_basic.result b/mysql-test/suite/sys_vars/r/innodb_monitor_disable_basic.result
index a20647487f5..e4b5bb4d21c 100644
--- a/mysql-test/suite/sys_vars/r/innodb_monitor_disable_basic.result
+++ b/mysql-test/suite/sys_vars/r/innodb_monitor_disable_basic.result
@@ -40,6 +40,8 @@ buffer_pages_written	disabled
 buffer_index_pages_written	disabled
 buffer_non_index_pages_written	disabled
 buffer_pages_read	disabled
+buffer_index_sec_rec_cluster_reads	disabled
+buffer_index_sec_rec_cluster_reads_avoided	disabled
 buffer_data_reads	disabled
 buffer_data_written	disabled
 buffer_flush_batch_scanned	disabled
diff --git a/mysql-test/suite/sys_vars/r/innodb_monitor_enable_basic.result b/mysql-test/suite/sys_vars/r/innodb_monitor_enable_basic.result
index a20647487f5..e4b5bb4d21c 100644
--- a/mysql-test/suite/sys_vars/r/innodb_monitor_enable_basic.result
+++ b/mysql-test/suite/sys_vars/r/innodb_monitor_enable_basic.result
@@ -40,6 +40,8 @@ buffer_pages_written	disabled
 buffer_index_pages_written	disabled
 buffer_non_index_pages_written	disabled
 buffer_pages_read	disabled
+buffer_index_sec_rec_cluster_reads	disabled
+buffer_index_sec_rec_cluster_reads_avoided	disabled
 buffer_data_reads	disabled
 buffer_data_written	disabled
 buffer_flush_batch_scanned	disabled
diff --git a/mysql-test/suite/sys_vars/r/innodb_monitor_reset_all_basic.result b/mysql-test/suite/sys_vars/r/innodb_monitor_reset_all_basic.result
index a20647487f5..e4b5bb4d21c 100644
--- a/mysql-test/suite/sys_vars/r/innodb_monitor_reset_all_basic.result
+++ b/mysql-test/suite/sys_vars/r/innodb_monitor_reset_all_basic.result
@@ -40,6 +40,8 @@ buffer_pages_written	disabled
 buffer_index_pages_written	disabled
 buffer_non_index_pages_written	disabled
 buffer_pages_read	disabled
+buffer_index_sec_rec_cluster_reads	disabled
+buffer_index_sec_rec_cluster_reads_avoided	disabled
 buffer_data_reads	disabled
 buffer_data_written	disabled
 buffer_flush_batch_scanned	disabled
diff --git a/mysql-test/suite/sys_vars/r/innodb_monitor_reset_basic.result b/mysql-test/suite/sys_vars/r/innodb_monitor_reset_basic.result
index a20647487f5..e4b5bb4d21c 100644
--- a/mysql-test/suite/sys_vars/r/innodb_monitor_reset_basic.result
+++ b/mysql-test/suite/sys_vars/r/innodb_monitor_reset_basic.result
@@ -40,6 +40,8 @@ buffer_pages_written	disabled
 buffer_index_pages_written	disabled
 buffer_non_index_pages_written	disabled
 buffer_pages_read	disabled
+buffer_index_sec_rec_cluster_reads	disabled
+buffer_index_sec_rec_cluster_reads_avoided	disabled
 buffer_data_reads	disabled
 buffer_data_written	disabled
 buffer_flush_batch_scanned	disabled
diff --git a/mysql-test/suite/sys_vars/r/innodb_prefix_index_cluster_optimization_basic.result b/mysql-test/suite/sys_vars/r/innodb_prefix_index_cluster_optimization_basic.result
new file mode 100644
index 00000000000..57b653bcf5e
--- /dev/null
+++ b/mysql-test/suite/sys_vars/r/innodb_prefix_index_cluster_optimization_basic.result
@@ -0,0 +1,122 @@
+SET @start_global_value = @@global.innodb_prefix_index_cluster_optimization;
+SELECT @start_global_value;
+@start_global_value
+0
+#
+# exists as global only
+#
+Valid values are 'ON' and 'OFF'
+select @@global.innodb_prefix_index_cluster_optimization in (0, 1);
+@@global.innodb_prefix_index_cluster_optimization in (0, 1)
+1
+select @@global.innodb_prefix_index_cluster_optimization;
+@@global.innodb_prefix_index_cluster_optimization
+0
+select @@session.innodb_prefix_index_cluster_optimization;
+ERROR HY000: Variable 'innodb_prefix_index_cluster_optimization' is a GLOBAL variable
+show global variables like 'innodb_prefix_index_cluster_optimization';
+Variable_name	Value
+innodb_prefix_index_cluster_optimization	OFF
+show session variables like 'innodb_prefix_index_cluster_optimization';
+Variable_name	Value
+innodb_prefix_index_cluster_optimization	OFF
+select * from information_schema.global_variables where variable_name = 'innodb_prefix_index_cluster_optimization';
+VARIABLE_NAME	VARIABLE_VALUE
+INNODB_PREFIX_INDEX_CLUSTER_OPTIMIZATION	OFF
+select * from information_schema.session_variables where variable_name = 'innodb_prefix_index_cluster_optimization';
+VARIABLE_NAME	VARIABLE_VALUE
+INNODB_PREFIX_INDEX_CLUSTER_OPTIMIZATION	OFF
+#
+# show that it's writable
+#
+set global innodb_prefix_index_cluster_optimization = 'OFF';
+select @@global.innodb_prefix_index_cluster_optimization;
+@@global.innodb_prefix_index_cluster_optimization
+0
+select * from information_schema.global_variables where variable_name = 'innodb_prefix_index_cluster_optimization';
+VARIABLE_NAME	VARIABLE_VALUE
+INNODB_PREFIX_INDEX_CLUSTER_OPTIMIZATION	OFF
+select * from information_schema.session_variables where variable_name = 'innodb_prefix_index_cluster_optimization';
+VARIABLE_NAME	VARIABLE_VALUE
+INNODB_PREFIX_INDEX_CLUSTER_OPTIMIZATION	OFF
+set @@global.innodb_prefix_index_cluster_optimization = 'ON';
+select @@global.innodb_prefix_index_cluster_optimization;
+@@global.innodb_prefix_index_cluster_optimization
+1
+select * from information_schema.global_variables where variable_name = 'innodb_prefix_index_cluster_optimization';
+VARIABLE_NAME	VARIABLE_VALUE
+INNODB_PREFIX_INDEX_CLUSTER_OPTIMIZATION	ON
+select * from information_schema.session_variables where variable_name = 'innodb_prefix_index_cluster_optimization';
+VARIABLE_NAME	VARIABLE_VALUE
+INNODB_PREFIX_INDEX_CLUSTER_OPTIMIZATION	ON
+set global innodb_prefix_index_cluster_optimization = 0;
+select @@global.innodb_prefix_index_cluster_optimization;
+@@global.innodb_prefix_index_cluster_optimization
+0
+select * from information_schema.global_variables where variable_name = 'innodb_prefix_index_cluster_optimization';
+VARIABLE_NAME	VARIABLE_VALUE
+INNODB_PREFIX_INDEX_CLUSTER_OPTIMIZATION	OFF
+select * from information_schema.session_variables where variable_name = 'innodb_prefix_index_cluster_optimization';
+VARIABLE_NAME	VARIABLE_VALUE
+INNODB_PREFIX_INDEX_CLUSTER_OPTIMIZATION	OFF
+set @@global.innodb_prefix_index_cluster_optimization = 1;
+select @@global.innodb_prefix_index_cluster_optimization;
+@@global.innodb_prefix_index_cluster_optimization
+1
+select * from information_schema.global_variables where variable_name = 'innodb_prefix_index_cluster_optimization';
+VARIABLE_NAME	VARIABLE_VALUE
+INNODB_PREFIX_INDEX_CLUSTER_OPTIMIZATION	ON
+select * from information_schema.session_variables where variable_name = 'innodb_prefix_index_cluster_optimization';
+VARIABLE_NAME	VARIABLE_VALUE
+INNODB_PREFIX_INDEX_CLUSTER_OPTIMIZATION	ON
+set session innodb_prefix_index_cluster_optimization = 'OFF';
+ERROR HY000: Variable 'innodb_prefix_index_cluster_optimization' is a GLOBAL variable and should be set with SET GLOBAL
+select @@global.innodb_prefix_index_cluster_optimization;
+@@global.innodb_prefix_index_cluster_optimization
+1
+select * from information_schema.global_variables where variable_name = 'innodb_prefix_index_cluster_optimization';
+VARIABLE_NAME	VARIABLE_VALUE
+INNODB_PREFIX_INDEX_CLUSTER_OPTIMIZATION	ON
+select * from information_schema.session_variables where variable_name = 'innodb_prefix_index_cluster_optimization';
+VARIABLE_NAME	VARIABLE_VALUE
+INNODB_PREFIX_INDEX_CLUSTER_OPTIMIZATION	ON
+set @@session.innodb_prefix_index_cluster_optimization = 'ON';
+ERROR HY000: Variable 'innodb_prefix_index_cluster_optimization' is a GLOBAL variable and should be set with SET GLOBAL
+select @@global.innodb_prefix_index_cluster_optimization;
+@@global.innodb_prefix_index_cluster_optimization
+1
+select * from information_schema.global_variables where variable_name = 'innodb_prefix_index_cluster_optimization';
+VARIABLE_NAME	VARIABLE_VALUE
+INNODB_PREFIX_INDEX_CLUSTER_OPTIMIZATION	ON
+select * from information_schema.session_variables where variable_name = 'innodb_prefix_index_cluster_optimization';
+VARIABLE_NAME	VARIABLE_VALUE
+INNODB_PREFIX_INDEX_CLUSTER_OPTIMIZATION	ON
+#
+# incorrect types
+#
+set global innodb_prefix_index_cluster_optimization = 1.1;
+ERROR 42000: Incorrect argument type to variable 'innodb_prefix_index_cluster_optimization'
+set global innodb_prefix_index_cluster_optimization = 1e1;
+ERROR 42000: Incorrect argument type to variable 'innodb_prefix_index_cluster_optimization'
+set global innodb_prefix_index_cluster_optimization = 2;
+ERROR 42000: Variable 'innodb_prefix_index_cluster_optimization' can't be set to the value of '2'
+set global innodb_prefix_index_cluster_optimization = -3;
+ERROR 42000: Variable 'innodb_prefix_index_cluster_optimization' can't be set to the value of '-3'
+select @@global.innodb_prefix_index_cluster_optimization;
+@@global.innodb_prefix_index_cluster_optimization
+1
+select * from information_schema.global_variables where variable_name = 'innodb_prefix_index_cluster_optimization';
+VARIABLE_NAME	VARIABLE_VALUE
+INNODB_PREFIX_INDEX_CLUSTER_OPTIMIZATION	ON
+select * from information_schema.session_variables where variable_name = 'innodb_prefix_index_cluster_optimization';
+VARIABLE_NAME	VARIABLE_VALUE
+INNODB_PREFIX_INDEX_CLUSTER_OPTIMIZATION	ON
+set global innodb_prefix_index_cluster_optimization = 'AUTO';
+ERROR 42000: Variable 'innodb_prefix_index_cluster_optimization' can't be set to the value of 'AUTO'
+#
+# Cleanup
+#
+SET @@global.innodb_prefix_index_cluster_optimization = @start_global_value;
+SELECT @@global.innodb_prefix_index_cluster_optimization;
+@@global.innodb_prefix_index_cluster_optimization
+0
diff --git a/mysql-test/suite/sys_vars/r/sysvars_innodb.result b/mysql-test/suite/sys_vars/r/sysvars_innodb.result
index c1823ff7739..6de55595e2d 100644
--- a/mysql-test/suite/sys_vars/r/sysvars_innodb.result
+++ b/mysql-test/suite/sys_vars/r/sysvars_innodb.result
@@ -1461,6 +1461,20 @@ NUMERIC_BLOCK_SIZE	0
 ENUM_VALUE_LIST	NULL
 READ_ONLY	YES
 COMMAND_LINE_ARGUMENT	OPTIONAL
+VARIABLE_NAME	INNODB_PREFIX_INDEX_CLUSTER_OPTIMIZATION
+SESSION_VALUE	NULL
+GLOBAL_VALUE	OFF
+GLOBAL_VALUE_ORIGIN	COMPILE-TIME
+DEFAULT_VALUE	OFF
+VARIABLE_SCOPE	GLOBAL
+VARIABLE_TYPE	BOOLEAN
+VARIABLE_COMMENT	Enable prefix optimization to sometimes avoid cluster index lookups.
+NUMERIC_MIN_VALUE	NULL
+NUMERIC_MAX_VALUE	NULL
+NUMERIC_BLOCK_SIZE	NULL
+ENUM_VALUE_LIST	NULL
+READ_ONLY	NO
+COMMAND_LINE_ARGUMENT	OPTIONAL
 VARIABLE_NAME	INNODB_PRINT_ALL_DEADLOCKS
 SESSION_VALUE	NULL
 GLOBAL_VALUE	OFF
diff --git a/mysql-test/suite/sys_vars/t/innodb_prefix_index_cluster_optimization_basic.test b/mysql-test/suite/sys_vars/t/innodb_prefix_index_cluster_optimization_basic.test
new file mode 100644
index 00000000000..4e272fbd9c5
--- /dev/null
+++ b/mysql-test/suite/sys_vars/t/innodb_prefix_index_cluster_optimization_basic.test
@@ -0,0 +1,76 @@
+--source include/have_innodb.inc
+
+SET @start_global_value = @@global.innodb_prefix_index_cluster_optimization;
+SELECT @start_global_value;
+
+--echo #
+--echo # exists as global only
+--echo #
+
+--echo Valid values are 'ON' and 'OFF'
+select @@global.innodb_prefix_index_cluster_optimization in (0, 1);
+select @@global.innodb_prefix_index_cluster_optimization;
+--error ER_INCORRECT_GLOBAL_LOCAL_VAR
+select @@session.innodb_prefix_index_cluster_optimization;
+show global variables like 'innodb_prefix_index_cluster_optimization';
+show session variables like 'innodb_prefix_index_cluster_optimization';
+select * from information_schema.global_variables where variable_name = 'innodb_prefix_index_cluster_optimization';
+select * from information_schema.session_variables where variable_name = 'innodb_prefix_index_cluster_optimization';
+
+--echo #
+--echo # show that it's writable
+--echo #
+
+set global innodb_prefix_index_cluster_optimization = 'OFF';
+select @@global.innodb_prefix_index_cluster_optimization;
+select * from information_schema.global_variables where variable_name = 'innodb_prefix_index_cluster_optimization';
+select * from information_schema.session_variables where variable_name = 'innodb_prefix_index_cluster_optimization';
+set @@global.innodb_prefix_index_cluster_optimization = 'ON';
+select @@global.innodb_prefix_index_cluster_optimization;
+select * from information_schema.global_variables where variable_name = 'innodb_prefix_index_cluster_optimization';
+select * from information_schema.session_variables where variable_name = 'innodb_prefix_index_cluster_optimization';
+set global innodb_prefix_index_cluster_optimization = 0;
+select @@global.innodb_prefix_index_cluster_optimization;
+select * from information_schema.global_variables where variable_name = 'innodb_prefix_index_cluster_optimization';
+select * from information_schema.session_variables where variable_name = 'innodb_prefix_index_cluster_optimization';
+set @@global.innodb_prefix_index_cluster_optimization = 1;
+select @@global.innodb_prefix_index_cluster_optimization;
+select * from information_schema.global_variables where variable_name = 'innodb_prefix_index_cluster_optimization';
+select * from information_schema.session_variables where variable_name = 'innodb_prefix_index_cluster_optimization';
+
+--error ER_GLOBAL_VARIABLE
+set session innodb_prefix_index_cluster_optimization = 'OFF';
+select @@global.innodb_prefix_index_cluster_optimization;
+select * from information_schema.global_variables where variable_name = 'innodb_prefix_index_cluster_optimization';
+select * from information_schema.session_variables where variable_name = 'innodb_prefix_index_cluster_optimization';
+
+--error ER_GLOBAL_VARIABLE
+set @@session.innodb_prefix_index_cluster_optimization = 'ON';
+select @@global.innodb_prefix_index_cluster_optimization;
+select * from information_schema.global_variables where variable_name = 'innodb_prefix_index_cluster_optimization';
+select * from information_schema.session_variables where variable_name = 'innodb_prefix_index_cluster_optimization';
+
+--echo #
+--echo # incorrect types
+--echo #
+
+--error ER_WRONG_TYPE_FOR_VAR
+set global innodb_prefix_index_cluster_optimization = 1.1;
+--error ER_WRONG_TYPE_FOR_VAR
+set global innodb_prefix_index_cluster_optimization = 1e1;
+--error ER_WRONG_VALUE_FOR_VAR
+set global innodb_prefix_index_cluster_optimization = 2;
+--error ER_WRONG_VALUE_FOR_VAR
+set global innodb_prefix_index_cluster_optimization = -3;
+select @@global.innodb_prefix_index_cluster_optimization;
+select * from information_schema.global_variables where variable_name = 'innodb_prefix_index_cluster_optimization';
+select * from information_schema.session_variables where variable_name = 'innodb_prefix_index_cluster_optimization';
+--error ER_WRONG_VALUE_FOR_VAR
+set global innodb_prefix_index_cluster_optimization = 'AUTO';
+
+--echo #
+--echo # Cleanup
+--echo #
+
+SET @@global.innodb_prefix_index_cluster_optimization = @start_global_value;
+SELECT @@global.innodb_prefix_index_cluster_optimization;
diff --git a/mysql-test/t/fast_prefix_index_fetch_innodb.test b/mysql-test/t/fast_prefix_index_fetch_innodb.test
new file mode 100644
index 00000000000..e563e65ec2a
--- /dev/null
+++ b/mysql-test/t/fast_prefix_index_fetch_innodb.test
@@ -0,0 +1,150 @@
+-- source include/have_innodb.inc
+
+--disable_warnings
+drop table if exists prefixinno;
+--enable_warnings
+
+set global innodb_prefix_index_cluster_optimization = ON;
+show variables like 'innodb_prefix_index_cluster_optimization';
+
+--echo # Create a table with a large varchar field that we index the prefix
+--echo # of and ensure we only trigger cluster lookups when we expect it.
+create table prefixinno (
+       id int not null,
+       fake_id int not null,
+       bigfield varchar(4096),
+       primary key(id),
+       index bigfield_idx (bigfield(32)),
+       index fake_id_bigfield_prefix (fake_id, bigfield(32))
+) engine=innodb;
+
+insert into prefixinno values (1, 1001, repeat('a', 1)),
+                              (8, 1008, repeat('b', 8)),
+                              (24, 1024, repeat('c', 24)),
+                              (31, 1031, repeat('d', 31)),
+                              (32, 1032, repeat('x', 32)),
+                              (33, 1033, repeat('y', 33)),
+                              (128, 1128, repeat('z', 128));
+
+select * from prefixinno;
+
+let $show_count_statement = show status like 'innodb_secondary_index_triggered_cluster_reads';
+let $show_opt_statement = show status like 'innodb_secondary_index_triggered_cluster_reads_avoided';
+
+--disable_query_log
+
+--echo # Baseline sanity check: 0, 0.
+--let $base_count = query_get_value($show_count_statement, Value, 1)
+--let $base_opt = query_get_value($show_opt_statement, Value, 1)
+select "no-op query";
+--let $count = query_get_value($show_count_statement, Value, 1)
+eval select $count - $base_count into @cluster_lookups;
+select @cluster_lookups = 0 as cluster_lookups_matched;
+--let $opt = query_get_value($show_opt_statement, Value, 1)
+eval select $opt - $base_opt into @cluster_lookups;
+select @cluster_lookups = 0 as cluster_lookups_avoided_matched;
+
+--echo # Eligible for optimization.
+--let $base_count = query_get_value($show_count_statement, Value, 1)
+--let $base_opt = query_get_value($show_opt_statement, Value, 1)
+select id, bigfield from prefixinno where bigfield = repeat('d', 31);
+--let $count = query_get_value($show_count_statement, Value, 1)
+eval select $count - $base_count into @cluster_lookups;
+select @cluster_lookups = 0 as cluster_lookups_matched;
+--let $opt = query_get_value($show_opt_statement, Value, 1)
+eval select $opt - $base_opt into @cluster_lookups;
+select @cluster_lookups = 1 as cluster_lookups_avoided_matched;
+
+--echo # Eligible for optimization, access via fake_id only.
+--let $base_count = query_get_value($show_count_statement, Value, 1)
+--let $base_opt = query_get_value($show_opt_statement, Value, 1)
+select id, bigfield from prefixinno where fake_id = 1031;
+--let $count = query_get_value($show_count_statement, Value, 1)
+eval select $count - $base_count into @cluster_lookups;
+select @cluster_lookups = 0 as cluster_lookups_matched;
+--let $opt = query_get_value($show_opt_statement, Value, 1)
+eval select $opt - $base_opt into @cluster_lookups;
+select @cluster_lookups = 1 as cluster_lookups_avoided_matched;
+
+--echo # Not eligible for optimization, access via fake_id of big row.
+--let $base_count = query_get_value($show_count_statement, Value, 1)
+--let $base_opt = query_get_value($show_opt_statement, Value, 1)
+select id, bigfield from prefixinno where fake_id = 1033;
+--let $count = query_get_value($show_count_statement, Value, 1)
+eval select $count - $base_count into @cluster_lookups;
+select @cluster_lookups = 1 as cluster_lookups_matched;
+--let $opt = query_get_value($show_opt_statement, Value, 1)
+eval select $opt - $base_opt into @cluster_lookups;
+select @cluster_lookups = 0 as cluster_lookups_avoided_matched;
+
+--echo # Not eligible for optimization.
+--let $base_count = query_get_value($show_count_statement, Value, 1)
+--let $base_opt = query_get_value($show_opt_statement, Value, 1)
+select id, bigfield from prefixinno where bigfield = repeat('x', 32);
+--let $count = query_get_value($show_count_statement, Value, 1)
+eval select $count - $base_count into @cluster_lookups;
+select @cluster_lookups = 1 as cluster_lookups_matched;
+--let $opt = query_get_value($show_opt_statement, Value, 1)
+eval select $opt - $base_opt into @cluster_lookups;
+select @cluster_lookups = 0 as cluster_lookups_avoided_matched;
+
+--echo # Not eligible for optimization.
+--let $base_count = query_get_value($show_count_statement, Value, 1)
+--let $base_opt = query_get_value($show_opt_statement, Value, 1)
+select id, bigfield from prefixinno where bigfield = repeat('y', 33);
+--let $count = query_get_value($show_count_statement, Value, 1)
+eval select $count - $base_count into @cluster_lookups;
+select @cluster_lookups = 1 as cluster_lookups_matched;
+--let $opt = query_get_value($show_opt_statement, Value, 1)
+eval select $opt - $base_opt into @cluster_lookups;
+select @cluster_lookups = 0 as cluster_lookups_avoided_matched;
+
+--echo # Eligible, should not increment lookup counter.
+--let $base_count = query_get_value($show_count_statement, Value, 1)
+--let $base_opt = query_get_value($show_opt_statement, Value, 1)
+select id, bigfield from prefixinno where bigfield = repeat('b', 8);
+--let $count = query_get_value($show_count_statement, Value, 1)
+eval select $count - $base_count into @cluster_lookups;
+select @cluster_lookups = 0 as cluster_lookups_matched;
+--let $opt = query_get_value($show_opt_statement, Value, 1)
+eval select $opt - $base_opt into @cluster_lookups;
+select @cluster_lookups = 1 as cluster_lookups_avoided_matched;
+
+--echo # Eligible, should not increment lookup counter.
+--let $base_count = query_get_value($show_count_statement, Value, 1)
+--let $base_opt = query_get_value($show_opt_statement, Value, 1)
+select id, bigfield from prefixinno where bigfield = repeat('c', 24);
+--let $count = query_get_value($show_count_statement, Value, 1)
+eval select $count - $base_count into @cluster_lookups;
+select @cluster_lookups = 0 as cluster_lookups_matched;
+--let $opt = query_get_value($show_opt_statement, Value, 1)
+eval select $opt - $base_opt into @cluster_lookups;
+select @cluster_lookups = 1 as cluster_lookups_avoided_matched;
+
+--echo # Should increment lookup counter.
+--let $base_count = query_get_value($show_count_statement, Value, 1)
+--let $base_opt = query_get_value($show_opt_statement, Value, 1)
+select id, bigfield from prefixinno where bigfield = repeat('z', 128);
+--let $count = query_get_value($show_count_statement, Value, 1)
+eval select $count - $base_count into @cluster_lookups;
+select @cluster_lookups = 1 as cluster_lookups_matched;
+--let $opt = query_get_value($show_opt_statement, Value, 1)
+eval select $opt - $base_opt into @cluster_lookups;
+select @cluster_lookups = 0 as cluster_lookups_avoided_matched;
+
+--echo # Disable optimization, confirm we still increment counter.
+--let $base_count = query_get_value($show_count_statement, Value, 1)
+--let $base_opt = query_get_value($show_opt_statement, Value, 1)
+set global innodb_prefix_index_cluster_optimization = OFF;
+select id, bigfield from prefixinno where fake_id = 1033;
+--let $count = query_get_value($show_count_statement, Value, 1)
+eval select $count - $base_count into @cluster_lookups;
+select @cluster_lookups = 1 as cluster_lookups_matched;
+--let $opt = query_get_value($show_opt_statement, Value, 1)
+eval select $opt - $base_opt into @cluster_lookups;
+select @cluster_lookups = 0 as cluster_lookups_avoided_matched;
+
+
+--echo # make test suite happy by cleaning up our mess
+drop table prefixinno;
+set global innodb_prefix_index_cluster_optimization = OFF;
diff --git a/storage/innobase/dict/dict0dict.cc b/storage/innobase/dict/dict0dict.cc
index 0b2073f6dc7..8fdc64a6152 100644
--- a/storage/innobase/dict/dict0dict.cc
+++ b/storage/innobase/dict/dict0dict.cc
@@ -748,17 +748,24 @@ dict_index_get_nth_col_or_prefix_pos(
 /*=================================*/
 	const dict_index_t*	index,		/*!< in: index */
 	ulint			n,		/*!< in: column number */
-	ibool			inc_prefix)	/*!< in: TRUE=consider
+	ibool			inc_prefix,	/*!< in: TRUE=consider
 						column prefixes too */
+	ulint*			prefix_col_pos)	/*!< out: col num if prefix */
 {
 	const dict_field_t*	field;
 	const dict_col_t*	col;
 	ulint			pos;
 	ulint			n_fields;
+	ulint			prefixed_pos_dummy;
 
 	ut_ad(index);
 	ut_ad(index->magic_n == DICT_INDEX_MAGIC_N);
 
+	if (!prefix_col_pos) {
+		prefix_col_pos = &prefixed_pos_dummy;
+	}
+	*prefix_col_pos = ULINT_UNDEFINED;
+
 	col = dict_table_get_nth_col(index->table, n);
 
 	if (dict_index_is_clust(index)) {
@@ -771,10 +778,11 @@ dict_index_get_nth_col_or_prefix_pos(
 	for (pos = 0; pos < n_fields; pos++) {
 		field = dict_index_get_nth_field(index, pos);
 
-		if (col == field->col
-		    && (inc_prefix || field->prefix_len == 0)) {
-
-			return(pos);
+		if (col == field->col) {
+			*prefix_col_pos = pos;
+			if (inc_prefix || field->prefix_len == 0) {
+				return(pos);
+			}
 		}
 	}
 
@@ -919,7 +927,7 @@ dict_table_get_nth_col_pos(
 	ulint			n)	/*!< in: column number */
 {
 	return(dict_index_get_nth_col_pos(dict_table_get_first_index(table),
-					  n));
+					  n, NULL));
 }
 
 /********************************************************************//**
diff --git a/storage/innobase/handler/ha_innodb.cc b/storage/innobase/handler/ha_innodb.cc
index ced6faba79b..8154c0fab6a 100644
--- a/storage/innobase/handler/ha_innodb.cc
+++ b/storage/innobase/handler/ha_innodb.cc
@@ -799,6 +799,14 @@ static SHOW_VAR innodb_status_variables[]= {
   {"onlineddl_pct_progress",
   (char*) &export_vars.innodb_onlineddl_pct_progress, SHOW_LONG},
 
+  /* Times secondary index lookup triggered cluster lookup and
+  times prefix optimization avoided triggering cluster lookup */
+  {"secondary_index_triggered_cluster_reads",
+  (char*) &export_vars.innodb_sec_rec_cluster_reads,	  SHOW_LONG},
+  {"secondary_index_triggered_cluster_reads_avoided",
+  (char*) &export_vars.innodb_sec_rec_cluster_reads_avoided, SHOW_LONG},
+
+
   {NullS, NullS, SHOW_LONG}
 };
 
@@ -7044,11 +7052,20 @@ build_template_field(
 	templ->col_no = i;
 	templ->clust_rec_field_no = dict_col_get_clust_pos(col, clust_index);
 	ut_a(templ->clust_rec_field_no != ULINT_UNDEFINED);
+	templ->rec_field_is_prefix = FALSE;
 
 	if (dict_index_is_clust(index)) {
 		templ->rec_field_no = templ->clust_rec_field_no;
+		templ->rec_prefix_field_no = ULINT_UNDEFINED;
 	} else {
-		templ->rec_field_no = dict_index_get_nth_col_pos(index, i);
+		/* If we're in a secondary index, keep track
+		* of the original index position even if this
+		* is just a prefix index; we will use this
+		* later to avoid a cluster index lookup in
+		* some cases.*/
+
+		templ->rec_field_no = dict_index_get_nth_col_pos(index, i,
+						&templ->rec_prefix_field_no);
 	}
 
 	if (field->real_maybe_null()) {
@@ -7079,6 +7096,13 @@ build_template_field(
 	if (!dict_index_is_clust(index)
 	    && templ->rec_field_no == ULINT_UNDEFINED) {
 		prebuilt->need_to_access_clustered = TRUE;
+
+		if (templ->rec_prefix_field_no != ULINT_UNDEFINED) {
+			dict_field_t* field = dict_index_get_nth_field(
+						index,
+						templ->rec_prefix_field_no);
+			templ->rec_field_is_prefix = (field->prefix_len != 0);
+		}
 	}
 
 	if (prebuilt->mysql_prefix_len < templ->mysql_col_offset
@@ -7240,7 +7264,8 @@ ha_innobase::build_template(
 				} else {
 					templ->icp_rec_field_no
 						= dict_index_get_nth_col_pos(
-							prebuilt->index, i);
+							prebuilt->index, i,
+							NULL);
 				}
 
 				if (dict_index_is_clust(prebuilt->index)) {
@@ -7270,7 +7295,7 @@ ha_innobase::build_template(
 
 				templ->icp_rec_field_no
 					= dict_index_get_nth_col_or_prefix_pos(
-						prebuilt->index, i, TRUE);
+						prebuilt->index, i, TRUE, NULL);
 				ut_ad(templ->icp_rec_field_no
 				      != ULINT_UNDEFINED);
 
@@ -18475,6 +18500,12 @@ static MYSQL_SYSVAR_ULONG(
   1000000, 0);			/* Maximum value */
 #endif /* HAVE_ATOMIC_BUILTINS */
 
+static MYSQL_SYSVAR_BOOL(prefix_index_cluster_optimization,
+  srv_prefix_index_cluster_optimization,
+  PLUGIN_VAR_OPCMDARG,
+  "Enable prefix optimization to sometimes avoid cluster index lookups.",
+  NULL, NULL, FALSE);
+
 static MYSQL_SYSVAR_ULONG(thread_sleep_delay, srv_thread_sleep_delay,
   PLUGIN_VAR_RQCMDARG,
   "Time of innodb thread sleeping before joining InnoDB queue (usec). "
@@ -18908,6 +18939,7 @@ static struct st_mysql_sys_var* innobase_system_variables[]= {
 #ifdef HAVE_ATOMIC_BUILTINS
   MYSQL_SYSVAR(adaptive_max_sleep_delay),
 #endif /* HAVE_ATOMIC_BUILTINS */
+  MYSQL_SYSVAR(prefix_index_cluster_optimization),
   MYSQL_SYSVAR(thread_sleep_delay),
   MYSQL_SYSVAR(autoinc_lock_mode),
   MYSQL_SYSVAR(version),
diff --git a/storage/innobase/handler/handler0alter.cc b/storage/innobase/handler/handler0alter.cc
index 329eae81854..74eb8d4a5b6 100644
--- a/storage/innobase/handler/handler0alter.cc
+++ b/storage/innobase/handler/handler0alter.cc
@@ -1194,7 +1194,8 @@ innobase_rec_to_mysql(
 
 		field->reset();
 
-		ipos = dict_index_get_nth_col_or_prefix_pos(index, i, TRUE);
+		ipos = dict_index_get_nth_col_or_prefix_pos(index, i, TRUE,
+							    NULL);
 
 		if (ipos == ULINT_UNDEFINED
 		    || rec_offs_nth_extern(offsets, ipos)) {
@@ -1246,7 +1247,8 @@ innobase_fields_to_mysql(
 
 		field->reset();
 
-		ipos = dict_index_get_nth_col_or_prefix_pos(index, i, TRUE);
+		ipos = dict_index_get_nth_col_or_prefix_pos(index, i, TRUE,
+							    NULL);
 
 		if (ipos == ULINT_UNDEFINED
 		    || dfield_is_ext(&fields[ipos])
diff --git a/storage/innobase/include/dict0dict.h b/storage/innobase/include/dict0dict.h
index b1a82b4b60f..c7161987b78 100644
--- a/storage/innobase/include/dict0dict.h
+++ b/storage/innobase/include/dict0dict.h
@@ -1159,8 +1159,9 @@ ulint
 dict_index_get_nth_col_pos(
 /*=======================*/
 	const dict_index_t*	index,	/*!< in: index */
-	ulint			n)	/*!< in: column number */
-	__attribute__((nonnull, warn_unused_result));
+	ulint			n,	/*!< in: column number */
+	ulint*			prefix_col_pos) /*!< out: col num if prefix */
+	__attribute__((nonnull(1), warn_unused_result));
 /********************************************************************//**
 Looks for column n in an index.
 @return position in internal representation of the index;
@@ -1171,9 +1172,11 @@ dict_index_get_nth_col_or_prefix_pos(
 /*=================================*/
 	const dict_index_t*	index,		/*!< in: index */
 	ulint			n,		/*!< in: column number */
-	ibool			inc_prefix)	/*!< in: TRUE=consider
+	ibool			inc_prefix,	/*!< in: TRUE=consider
 						column prefixes too */
-	__attribute__((nonnull, warn_unused_result));
+	ulint*			prefix_col_pos)	/*!< out: col num if prefix */
+
+	__attribute__((nonnull(1), warn_unused_result));
 /********************************************************************//**
 Returns TRUE if the index contains a column or a prefix of that column.
 @return	TRUE if contains the column or its prefix */
diff --git a/storage/innobase/include/dict0dict.ic b/storage/innobase/include/dict0dict.ic
index 84d5c57f720..43bd42ae025 100644
--- a/storage/innobase/include/dict0dict.ic
+++ b/storage/innobase/include/dict0dict.ic
@@ -1221,7 +1221,8 @@ dict_index_get_sys_col_pos(
 	}
 
 	return(dict_index_get_nth_col_pos(
-		       index, dict_table_get_sys_col_no(index->table, type)));
+			index, dict_table_get_sys_col_no(index->table, type),
+			NULL));
 }
 
 /*********************************************************************//**
@@ -1273,9 +1274,11 @@ ulint
 dict_index_get_nth_col_pos(
 /*=======================*/
 	const dict_index_t*	index,	/*!< in: index */
-	ulint			n)	/*!< in: column number */
+	ulint			n,	/*!< in: column number */
+	ulint*			prefix_col_pos) /*!< out: col num if prefix */
 {
-	return(dict_index_get_nth_col_or_prefix_pos(index, n, FALSE));
+	return(dict_index_get_nth_col_or_prefix_pos(index, n, FALSE,
+						    prefix_col_pos));
 }
 
 #ifndef UNIV_HOTBACKUP
diff --git a/storage/innobase/include/row0mysql.h b/storage/innobase/include/row0mysql.h
index 1e0f3b30f8c..3cff5a41b8e 100644
--- a/storage/innobase/include/row0mysql.h
+++ b/storage/innobase/include/row0mysql.h
@@ -606,6 +606,12 @@ struct mysql_row_templ_t {
 					Innobase record in the current index;
 					not defined if template_type is
 					ROW_MYSQL_WHOLE_ROW */
+	ibool	rec_field_is_prefix;	/* is this field in a prefix index? */
+	ulint	rec_prefix_field_no;	/* record field, even if just a
+					prefix; same as rec_field_no when not a
+					prefix, otherwise rec_field_no is
+					ULINT_UNDEFINED but this is the true
+					field number*/
 	ulint	clust_rec_field_no;	/*!< field number of the column in an
 					Innobase record in the clustered index;
 					not defined if template_type is
@@ -707,7 +713,9 @@ struct row_prebuilt_t {
 					columns through a secondary index
 					and at least one column is not in
 					the secondary index, then this is
-					set to TRUE */
+					set to TRUE; note that sometimes this
+					is set but we later optimize out the
+					clustered index lookup */
 	unsigned	templ_contains_blob:1;/*!< TRUE if the template contains
 					a column with DATA_BLOB ==
 					get_innobase_type_from_mysql_type();
diff --git a/storage/innobase/include/srv0mon.h b/storage/innobase/include/srv0mon.h
index dccf2d99bb0..00ec2925441 100644
--- a/storage/innobase/include/srv0mon.h
+++ b/storage/innobase/include/srv0mon.h
@@ -167,6 +167,8 @@ enum monitor_id_t {
 	MONITOR_OVLD_INDEX_PAGES_WRITTEN,
 	MONITOR_OVLD_NON_INDEX_PAGES_WRITTEN,
 	MONITOR_OVLD_PAGES_READ,
+	MONITOR_OVLD_INDEX_SEC_REC_CLUSTER_READS,
+	MONITOR_OVLD_INDEX_SEC_REC_CLUSTER_READS_AVOIDED,
 	MONITOR_OVLD_BYTE_READ,
 	MONITOR_OVLD_BYTE_WRITTEN,
 	MONITOR_FLUSH_BATCH_SCANNED,
diff --git a/storage/innobase/include/srv0srv.h b/storage/innobase/include/srv0srv.h
index e3ac49c50ac..f628632c616 100644
--- a/storage/innobase/include/srv0srv.h
+++ b/storage/innobase/include/srv0srv.h
@@ -157,6 +157,12 @@ struct srv_stats_t {
 
 	/** Number of rows inserted */
 	ulint_ctr_64_t		n_rows_inserted;
+
+	/** Number of times secondary index lookup triggered cluster lookup */
+	ulint_ctr_64_t		n_sec_rec_cluster_reads;
+
+	/** Number of times prefix optimization avoided triggering cluster lookup */
+	ulint_ctr_64_t		n_sec_rec_cluster_reads_avoided;
 };
 
 extern const char*	srv_main_thread_op_info;
@@ -304,6 +310,10 @@ extern ulong	srv_auto_extend_increment;
 
 extern ibool	srv_created_new_raw;
 
+/* Optimize prefix index queries to skip cluster index lookup when possible */
+/* Enables or disables this prefix optimization.  Disabled by default. */
+extern my_bool	srv_prefix_index_cluster_optimization;
+
 /** Maximum number of srv_n_log_files, or innodb_log_files_in_group */
 #define SRV_N_LOG_FILES_MAX 100
 extern ulong	srv_n_log_files;
@@ -969,6 +979,9 @@ struct export_var_t{
 						compression */
 	ib_int64_t innodb_pages_page_compression_error;/*!< Number of page
 						compression errors */
+
+	ulint innodb_sec_rec_cluster_reads;	/*!< srv_sec_rec_cluster_reads */
+	ulint innodb_sec_rec_cluster_reads_avoided; /*!< srv_sec_rec_cluster_reads_avoided */
 };
 
 /** Thread slot in the thread table.  */
diff --git a/storage/innobase/pars/pars0opt.cc b/storage/innobase/pars/pars0opt.cc
index cbed2b39eeb..5a7e1861d74 100644
--- a/storage/innobase/pars/pars0opt.cc
+++ b/storage/innobase/pars/pars0opt.cc
@@ -948,12 +948,14 @@ opt_find_all_cols(
 	/* Fill in the field_no fields in sym_node */
 
 	sym_node->field_nos[SYM_CLUST_FIELD_NO] = dict_index_get_nth_col_pos(
-		dict_table_get_first_index(index->table), sym_node->col_no);
+		dict_table_get_first_index(index->table), sym_node->col_no,
+		NULL);
 	if (!dict_index_is_clust(index)) {
 
 		ut_a(plan);
 
-		col_pos = dict_index_get_nth_col_pos(index, sym_node->col_no);
+		col_pos = dict_index_get_nth_col_pos(index, sym_node->col_no,
+						     NULL);
 
 		if (col_pos == ULINT_UNDEFINED) {
 
diff --git a/storage/innobase/pars/pars0pars.cc b/storage/innobase/pars/pars0pars.cc
index 655e5ba1324..c87e1f8e247 100644
--- a/storage/innobase/pars/pars0pars.cc
+++ b/storage/innobase/pars/pars0pars.cc
@@ -1232,7 +1232,8 @@ pars_process_assign_list(
 		col_sym = assign_node->col;
 
 		upd_field_set_field_no(upd_field, dict_index_get_nth_col_pos(
-					       clust_index, col_sym->col_no),
+						clust_index, col_sym->col_no,
+						NULL),
 				       clust_index, NULL);
 		upd_field->exp = assign_node->val;
 
diff --git a/storage/innobase/row/row0sel.cc b/storage/innobase/row/row0sel.cc
index e5a7694cb93..d888c1ef645 100644
--- a/storage/innobase/row/row0sel.cc
+++ b/storage/innobase/row/row0sel.cc
@@ -56,6 +56,7 @@ Created 12/19/1997 Heikki Tuuri
 #include "row0mysql.h"
 #include "read0read.h"
 #include "buf0lru.h"
+#include "srv0srv.h"
 #include "ha_prototypes.h"
 #include "m_string.h" /* for my_sys.h */
 #include "my_sys.h" /* DEBUG_SYNC_C */
@@ -2936,9 +2937,14 @@ row_sel_store_mysql_rec(
 			: templ->rec_field_no;
 		/* We should never deliver column prefixes to MySQL,
 		except for evaluating innobase_index_cond(). */
+		/* ...actually, we do want to do this in order to
+		support the prefix query optimization.
+
 		ut_ad(dict_index_get_nth_field(index, field_no)->prefix_len
 		      == 0);
 
+		...so we disable this assert. */
+
 		if (!row_sel_store_mysql_field(mysql_rec, prebuilt,
 					       rec, index, offsets,
 					       field_no, templ)) {
@@ -3031,6 +3037,8 @@ row_sel_get_clust_rec_for_mysql(
 	dberr_t		err;
 	trx_t*		trx;
 
+	srv_stats.n_sec_rec_cluster_reads.inc();
+
 	*out_rec = NULL;
 	trx = thr_get_trx(thr);
 
@@ -3686,6 +3694,7 @@ row_search_for_mysql(
 	ulint*		offsets				= offsets_;
 	ibool		table_lock_waited		= FALSE;
 	byte*		next_buf			= 0;
+	ibool		use_clustered_index		= FALSE;
 
 	rec_offs_init(offsets_);
 
@@ -4709,10 +4718,68 @@ locks_ok:
 	}
 
 	/* Get the clustered index record if needed, if we did not do the
-	search using the clustered index. */
+	search using the clustered index... */
 
-	if (index != clust_index && prebuilt->need_to_access_clustered) {
+	use_clustered_index =
+		(index != clust_index && prebuilt->need_to_access_clustered);
 
+	if (use_clustered_index && srv_prefix_index_cluster_optimization
+	    && prebuilt->n_template <= index->n_fields) {
+		/* ...but, perhaps avoid the clustered index lookup if
+		all of the following are true:
+		1) all columns are in the secondary index
+		2) all values for columns that are prefix-only
+		   indexes are shorter than the prefix size
+		This optimization can avoid many IOs for certain schemas.
+		*/
+		ibool row_contains_all_values = TRUE;
+		int i;
+		for (i = 0; i < prebuilt->n_template; i++) {
+			/* Condition (1) from above: is the field in the
+			index (prefix or not)? */
+			mysql_row_templ_t* templ =
+				prebuilt->mysql_template + i;
+			ulint secondary_index_field_no =
+				templ->rec_prefix_field_no;
+			if (secondary_index_field_no == ULINT_UNDEFINED) {
+				row_contains_all_values = FALSE;
+				break;
+			}
+			/* Condition (2) from above: if this is a
+			prefix, is this row's value size shorter
+			than the prefix? */
+			if (templ->rec_field_is_prefix) {
+				ulint record_size = rec_offs_nth_size(
+					offsets,
+					secondary_index_field_no);
+				const dict_field_t *field =
+					dict_index_get_nth_field(
+						index,
+						secondary_index_field_no);
+				ut_a(field->prefix_len > 0);
+				if (record_size >= field->prefix_len) {
+					row_contains_all_values = FALSE;
+					break;
+				}
+			}
+		}
+		/* If (1) and (2) were true for all columns above, use
+		rec_prefix_field_no instead of rec_field_no, and skip
+		the clustered lookup below. */
+		if (row_contains_all_values) {
+			for (i = 0; i < prebuilt->n_template; i++) {
+				mysql_row_templ_t* templ =
+					prebuilt->mysql_template + i;
+				templ->rec_field_no =
+					templ->rec_prefix_field_no;
+				ut_a(templ->rec_field_no != ULINT_UNDEFINED);
+			}
+			use_clustered_index = FALSE;
+			srv_stats.n_sec_rec_cluster_reads_avoided.inc();
+		}
+	}
+
+	if (use_clustered_index) {
 requires_clust_rec:
 		ut_ad(index != clust_index);
 		/* We use a 'goto' to the preceding label if a consistent
diff --git a/storage/innobase/srv/srv0mon.cc b/storage/innobase/srv/srv0mon.cc
index 7be25966557..44e228dc523 100644
--- a/storage/innobase/srv/srv0mon.cc
+++ b/storage/innobase/srv/srv0mon.cc
@@ -309,6 +309,18 @@ static monitor_info_t	innodb_counter_info[] =
 	 MONITOR_EXISTING | MONITOR_DEFAULT_ON),
 	 MONITOR_DEFAULT_START, MONITOR_OVLD_PAGES_READ},
 
+	{"buffer_index_sec_rec_cluster_reads", "buffer",
+	 "Number of secondary record reads triggered cluster read",
+	 static_cast<monitor_type_t>(
+	 MONITOR_EXISTING | MONITOR_DEFAULT_ON),
+	 MONITOR_DEFAULT_START, MONITOR_OVLD_INDEX_SEC_REC_CLUSTER_READS},
+
+	{"buffer_index_sec_rec_cluster_reads_avoided", "buffer",
+	 "Number of secondary record reads avoided triggering cluster read",
+	 static_cast<monitor_type_t>(
+	 MONITOR_EXISTING | MONITOR_DEFAULT_ON),
+	 MONITOR_DEFAULT_START, MONITOR_OVLD_INDEX_SEC_REC_CLUSTER_READS_AVOIDED},
+
 	{"buffer_data_reads", "buffer",
 	 "Amount of data read in bytes (innodb_data_reads)",
 	 static_cast<monitor_type_t>(
@@ -1646,6 +1658,16 @@ srv_mon_process_existing_counter(
 		value = stat.n_pages_read;
 		break;
 
+	/* Number of times secondary index lookup triggered cluster lookup */
+	case MONITOR_OVLD_INDEX_SEC_REC_CLUSTER_READS:
+		value = srv_stats.n_sec_rec_cluster_reads;
+		break;
+	/* Number of times prefix optimization avoided triggering cluster
+	lookup */
+	case MONITOR_OVLD_INDEX_SEC_REC_CLUSTER_READS_AVOIDED:
+		value = srv_stats.n_sec_rec_cluster_reads_avoided;
+		break;
+
 	/* innodb_data_reads, the total number of data reads */
 	case MONITOR_OVLD_BYTE_READ:
 		value = srv_stats.data_read;
diff --git a/storage/innobase/srv/srv0srv.cc b/storage/innobase/srv/srv0srv.cc
index 5dfb38b53c7..796fe4c9c59 100644
--- a/storage/innobase/srv/srv0srv.cc
+++ b/storage/innobase/srv/srv0srv.cc
@@ -356,6 +356,10 @@ UNIV_INTERN ulint	srv_fast_shutdown	= 0;
 /* Generate a innodb_status.<pid> file */
 UNIV_INTERN ibool	srv_innodb_status	= FALSE;
 
+/* Optimize prefix index queries to skip cluster index lookup when possible */
+/* Enables or disables this prefix optimization.  Disabled by default. */
+UNIV_INTERN my_bool	srv_prefix_index_cluster_optimization = 0;
+
 /* When estimating number of different key values in an index, sample
 this many index pages, there are 2 ways to calculate statistics:
 * persistent stats that are calculated by ANALYZE TABLE and saved
@@ -1566,6 +1570,11 @@ srv_export_innodb_status(void)
 	}
 #endif /* UNIV_DEBUG */
 
+	export_vars.innodb_sec_rec_cluster_reads =
+		srv_stats.n_sec_rec_cluster_reads;
+	export_vars.innodb_sec_rec_cluster_reads_avoided =
+		srv_stats.n_sec_rec_cluster_reads_avoided;
+
 	mutex_exit(&srv_innodb_monitor_mutex);
 }
 
diff --git a/storage/innobase/trx/trx0rec.cc b/storage/innobase/trx/trx0rec.cc
index a698b37c2a6..4d3458ff8bb 100644
--- a/storage/innobase/trx/trx0rec.cc
+++ b/storage/innobase/trx/trx0rec.cc
@@ -781,7 +781,8 @@ trx_undo_page_report_modify(
 				}
 
 				pos = dict_index_get_nth_col_pos(index,
-								 col_no);
+								 col_no,
+								 NULL);
 				ptr += mach_write_compressed(ptr, pos);
 
 				/* Save the old value of field */
diff --git a/storage/xtradb/dict/dict0dict.cc b/storage/xtradb/dict/dict0dict.cc
index 05169cbbaa0..1292c888e58 100644
--- a/storage/xtradb/dict/dict0dict.cc
+++ b/storage/xtradb/dict/dict0dict.cc
@@ -748,17 +748,24 @@ dict_index_get_nth_col_or_prefix_pos(
 /*=================================*/
 	const dict_index_t*	index,		/*!< in: index */
 	ulint			n,		/*!< in: column number */
-	ibool			inc_prefix)	/*!< in: TRUE=consider
+	ibool			inc_prefix,	/*!< in: TRUE=consider
 						column prefixes too */
+	ulint*			prefix_col_pos)	/*!< out: col num if prefix */
 {
 	const dict_field_t*	field;
 	const dict_col_t*	col;
 	ulint			pos;
 	ulint			n_fields;
+	ulint			prefixed_pos_dummy;
 
 	ut_ad(index);
 	ut_ad(index->magic_n == DICT_INDEX_MAGIC_N);
 
+	if (!prefix_col_pos) {
+		prefix_col_pos = &prefixed_pos_dummy;
+	}
+	*prefix_col_pos = ULINT_UNDEFINED;
+
 	col = dict_table_get_nth_col(index->table, n);
 
 	if (dict_index_is_clust(index)) {
@@ -771,10 +778,11 @@ dict_index_get_nth_col_or_prefix_pos(
 	for (pos = 0; pos < n_fields; pos++) {
 		field = dict_index_get_nth_field(index, pos);
 
-		if (col == field->col
-		    && (inc_prefix || field->prefix_len == 0)) {
-
-			return(pos);
+		if (col == field->col) {
+			*prefix_col_pos = pos;
+			if (inc_prefix || field->prefix_len == 0) {
+				return(pos);
+			}
 		}
 	}
 
@@ -919,7 +927,7 @@ dict_table_get_nth_col_pos(
 	ulint			n)	/*!< in: column number */
 {
 	return(dict_index_get_nth_col_pos(dict_table_get_first_index(table),
-					  n));
+					  n, NULL));
 }
 
 /********************************************************************//**
diff --git a/storage/xtradb/handler/ha_innodb.cc b/storage/xtradb/handler/ha_innodb.cc
index 93563b16c13..f3b11672735 100644
--- a/storage/xtradb/handler/ha_innodb.cc
+++ b/storage/xtradb/handler/ha_innodb.cc
@@ -998,6 +998,14 @@ static SHOW_VAR innodb_status_variables[]= {
   {"onlineddl_pct_progress",
   (char*) &export_vars.innodb_onlineddl_pct_progress, SHOW_LONG},
 
+  /* Times secondary index lookup triggered cluster lookup and
+  times prefix optimization avoided triggering cluster lookup */
+  {"secondary_index_triggered_cluster_reads",
+  (char*) &export_vars.innodb_sec_rec_cluster_reads,	  SHOW_LONG},
+  {"secondary_index_triggered_cluster_reads_avoided",
+  (char*) &export_vars.innodb_sec_rec_cluster_reads_avoided, SHOW_LONG},
+
+
   {NullS, NullS, SHOW_LONG}
 };
 
@@ -7615,11 +7623,20 @@ build_template_field(
 	templ->col_no = i;
 	templ->clust_rec_field_no = dict_col_get_clust_pos(col, clust_index);
 	ut_a(templ->clust_rec_field_no != ULINT_UNDEFINED);
+	templ->rec_field_is_prefix = FALSE;
 
 	if (dict_index_is_clust(index)) {
 		templ->rec_field_no = templ->clust_rec_field_no;
+		templ->rec_prefix_field_no = ULINT_UNDEFINED;
 	} else {
-		templ->rec_field_no = dict_index_get_nth_col_pos(index, i);
+		/* If we're in a secondary index, keep track
+		* of the original index position even if this
+		* is just a prefix index; we will use this
+		* later to avoid a cluster index lookup in
+		* some cases.*/
+
+		templ->rec_field_no = dict_index_get_nth_col_pos(index, i,
+						&templ->rec_prefix_field_no);
 	}
 
 	if (field->real_maybe_null()) {
@@ -7650,6 +7667,13 @@ build_template_field(
 	if (!dict_index_is_clust(index)
 	    && templ->rec_field_no == ULINT_UNDEFINED) {
 		prebuilt->need_to_access_clustered = TRUE;
+
+		if (templ->rec_prefix_field_no != ULINT_UNDEFINED) {
+			dict_field_t* field = dict_index_get_nth_field(
+						index,
+						templ->rec_prefix_field_no);
+			templ->rec_field_is_prefix = (field->prefix_len != 0);
+		}
 	}
 
 	if (prebuilt->mysql_prefix_len < templ->mysql_col_offset
@@ -7811,7 +7835,8 @@ ha_innobase::build_template(
 				} else {
 					templ->icp_rec_field_no
 						= dict_index_get_nth_col_pos(
-							prebuilt->index, i);
+							prebuilt->index, i,
+							NULL);
 				}
 
 				if (dict_index_is_clust(prebuilt->index)) {
@@ -7841,7 +7866,7 @@ ha_innobase::build_template(
 
 				templ->icp_rec_field_no
 					= dict_index_get_nth_col_or_prefix_pos(
-						prebuilt->index, i, TRUE);
+						prebuilt->index, i, TRUE, NULL);
 				ut_ad(templ->icp_rec_field_no
 				      != ULINT_UNDEFINED);
 
@@ -19705,6 +19730,12 @@ static MYSQL_SYSVAR_ULONG(
   1000000, 0);			/* Maximum value */
 #endif /* HAVE_ATOMIC_BUILTINS */
 
+static MYSQL_SYSVAR_BOOL(prefix_index_cluster_optimization,
+  srv_prefix_index_cluster_optimization,
+  PLUGIN_VAR_OPCMDARG,
+  "Enable prefix optimization to sometimes avoid cluster index lookups.",
+  NULL, NULL, FALSE);
+
 static MYSQL_SYSVAR_ULONG(thread_sleep_delay, srv_thread_sleep_delay,
   PLUGIN_VAR_RQCMDARG,
   "Time of innodb thread sleeping before joining InnoDB queue (usec). "
@@ -20207,6 +20238,7 @@ static struct st_mysql_sys_var* innobase_system_variables[]= {
 #ifdef HAVE_ATOMIC_BUILTINS
   MYSQL_SYSVAR(adaptive_max_sleep_delay),
 #endif /* HAVE_ATOMIC_BUILTINS */
+  MYSQL_SYSVAR(prefix_index_cluster_optimization),
   MYSQL_SYSVAR(thread_sleep_delay),
   MYSQL_SYSVAR(autoinc_lock_mode),
   MYSQL_SYSVAR(show_verbose_locks),
diff --git a/storage/xtradb/handler/handler0alter.cc b/storage/xtradb/handler/handler0alter.cc
index 2d7fd259cb1..85c77f4d8a2 100644
--- a/storage/xtradb/handler/handler0alter.cc
+++ b/storage/xtradb/handler/handler0alter.cc
@@ -1199,7 +1199,8 @@ innobase_rec_to_mysql(
 
 		field->reset();
 
-		ipos = dict_index_get_nth_col_or_prefix_pos(index, i, TRUE);
+		ipos = dict_index_get_nth_col_or_prefix_pos(index, i, TRUE,
+							    NULL);
 
 		if (ipos == ULINT_UNDEFINED
 		    || rec_offs_nth_extern(offsets, ipos)) {
@@ -1251,7 +1252,8 @@ innobase_fields_to_mysql(
 
 		field->reset();
 
-		ipos = dict_index_get_nth_col_or_prefix_pos(index, i, TRUE);
+		ipos = dict_index_get_nth_col_or_prefix_pos(index, i, TRUE,
+							    NULL);
 
 		if (ipos == ULINT_UNDEFINED
 		    || dfield_is_ext(&fields[ipos])
diff --git a/storage/xtradb/include/dict0dict.h b/storage/xtradb/include/dict0dict.h
index 78503d954ba..2642f8b1767 100644
--- a/storage/xtradb/include/dict0dict.h
+++ b/storage/xtradb/include/dict0dict.h
@@ -1158,8 +1158,9 @@ ulint
 dict_index_get_nth_col_pos(
 /*=======================*/
 	const dict_index_t*	index,	/*!< in: index */
-	ulint			n)	/*!< in: column number */
-	__attribute__((nonnull, warn_unused_result));
+	ulint			n,	/*!< in: column number */
+	ulint*			prefix_col_pos) /*!< out: col num if prefix */
+	__attribute__((nonnull(1), warn_unused_result));
 /********************************************************************//**
 Looks for column n in an index.
 @return position in internal representation of the index;
@@ -1170,9 +1171,11 @@ dict_index_get_nth_col_or_prefix_pos(
 /*=================================*/
 	const dict_index_t*	index,		/*!< in: index */
 	ulint			n,		/*!< in: column number */
-	ibool			inc_prefix)	/*!< in: TRUE=consider
+	ibool			inc_prefix,	/*!< in: TRUE=consider
 						column prefixes too */
-	__attribute__((nonnull, warn_unused_result));
+	ulint*			prefix_col_pos)	/*!< out: col num if prefix */
+
+	__attribute__((nonnull(1), warn_unused_result));
 /********************************************************************//**
 Returns TRUE if the index contains a column or a prefix of that column.
 @return	TRUE if contains the column or its prefix */
diff --git a/storage/xtradb/include/dict0dict.ic b/storage/xtradb/include/dict0dict.ic
index 2b698dd7218..676d09b7268 100644
--- a/storage/xtradb/include/dict0dict.ic
+++ b/storage/xtradb/include/dict0dict.ic
@@ -1225,7 +1225,8 @@ dict_index_get_sys_col_pos(
 	}
 
 	return(dict_index_get_nth_col_pos(
-		       index, dict_table_get_sys_col_no(index->table, type)));
+			index, dict_table_get_sys_col_no(index->table, type),
+			NULL));
 }
 
 /*********************************************************************//**
@@ -1277,9 +1278,11 @@ ulint
 dict_index_get_nth_col_pos(
 /*=======================*/
 	const dict_index_t*	index,	/*!< in: index */
-	ulint			n)	/*!< in: column number */
+	ulint			n,	/*!< in: column number */
+	ulint*			prefix_col_pos) /*!< out: col num if prefix */
 {
-	return(dict_index_get_nth_col_or_prefix_pos(index, n, FALSE));
+	return(dict_index_get_nth_col_or_prefix_pos(index, n, FALSE,
+						    prefix_col_pos));
 }
 
 #ifndef UNIV_HOTBACKUP
diff --git a/storage/xtradb/include/row0mysql.h b/storage/xtradb/include/row0mysql.h
index cd37a2f69bb..597d0043134 100644
--- a/storage/xtradb/include/row0mysql.h
+++ b/storage/xtradb/include/row0mysql.h
@@ -606,6 +606,12 @@ struct mysql_row_templ_t {
 					Innobase record in the current index;
 					not defined if template_type is
 					ROW_MYSQL_WHOLE_ROW */
+	ibool	rec_field_is_prefix;	/* is this field in a prefix index? */
+	ulint	rec_prefix_field_no;	/* record field, even if just a
+					prefix; same as rec_field_no when not a
+					prefix, otherwise rec_field_no is
+					ULINT_UNDEFINED but this is the true
+					field number*/
 	ulint	clust_rec_field_no;	/*!< field number of the column in an
 					Innobase record in the clustered index;
 					not defined if template_type is
@@ -708,7 +714,9 @@ struct row_prebuilt_t {
 					columns through a secondary index
 					and at least one column is not in
 					the secondary index, then this is
-					set to TRUE */
+					set to TRUE; note that sometimes this
+					is set but we later optimize out the
+					clustered index lookup */
 	unsigned	templ_contains_blob:1;/*!< TRUE if the template contains
 					a column with DATA_BLOB ==
 					get_innobase_type_from_mysql_type();
diff --git a/storage/xtradb/include/srv0mon.h b/storage/xtradb/include/srv0mon.h
index c1585c3072c..2dcf3ed480e 100644
--- a/storage/xtradb/include/srv0mon.h
+++ b/storage/xtradb/include/srv0mon.h
@@ -167,6 +167,8 @@ enum monitor_id_t {
 	MONITOR_OVLD_INDEX_PAGES_WRITTEN,
 	MONITOR_OVLD_NON_INDEX_PAGES_WRITTEN,
 	MONITOR_OVLD_PAGES_READ,
+	MONITOR_OVLD_INDEX_SEC_REC_CLUSTER_READS,
+	MONITOR_OVLD_INDEX_SEC_REC_CLUSTER_READS_AVOIDED,
 	MONITOR_OVLD_BYTE_READ,
 	MONITOR_OVLD_BYTE_WRITTEN,
 	MONITOR_FLUSH_BATCH_SCANNED,
diff --git a/storage/xtradb/include/srv0srv.h b/storage/xtradb/include/srv0srv.h
index 2825e37ba86..e47b6f1751d 100644
--- a/storage/xtradb/include/srv0srv.h
+++ b/storage/xtradb/include/srv0srv.h
@@ -158,6 +158,12 @@ struct srv_stats_t {
 	/** Number of rows inserted */
 	ulint_ctr_64_t		n_rows_inserted;
 
+	/** Number of times secondary index lookup triggered cluster lookup */
+	ulint_ctr_64_t		n_sec_rec_cluster_reads;
+
+	/** Number of times prefix optimization avoided triggering cluster lookup */
+	ulint_ctr_64_t		n_sec_rec_cluster_reads_avoided;
+
 	ulint_ctr_1_t		lock_deadlock_count;
 
 	ulint_ctr_1_t		n_lock_max_wait_time;
@@ -326,6 +332,10 @@ extern ulong	srv_auto_extend_increment;
 
 extern ibool	srv_created_new_raw;
 
+/* Optimize prefix index queries to skip cluster index lookup when possible */
+/* Enables or disables this prefix optimization.  Disabled by default. */
+extern my_bool	srv_prefix_index_cluster_optimization;
+
 /** Maximum number of srv_n_log_files, or innodb_log_files_in_group */
 #define SRV_N_LOG_FILES_MAX 100
 extern ulong	srv_n_log_files;
@@ -1183,6 +1193,9 @@ struct export_var_t{
 						compression */
 	ib_int64_t innodb_pages_page_compression_error;/*!< Number of page
 						compression errors */
+
+	ulint innodb_sec_rec_cluster_reads;	/*!< srv_sec_rec_cluster_reads */
+	ulint innodb_sec_rec_cluster_reads_avoided; /*!< srv_sec_rec_cluster_reads_avoided */
 };
 
 /** Thread slot in the thread table.  */
diff --git a/storage/xtradb/pars/pars0opt.cc b/storage/xtradb/pars/pars0opt.cc
index cbed2b39eeb..5a7e1861d74 100644
--- a/storage/xtradb/pars/pars0opt.cc
+++ b/storage/xtradb/pars/pars0opt.cc
@@ -948,12 +948,14 @@ opt_find_all_cols(
 	/* Fill in the field_no fields in sym_node */
 
 	sym_node->field_nos[SYM_CLUST_FIELD_NO] = dict_index_get_nth_col_pos(
-		dict_table_get_first_index(index->table), sym_node->col_no);
+		dict_table_get_first_index(index->table), sym_node->col_no,
+		NULL);
 	if (!dict_index_is_clust(index)) {
 
 		ut_a(plan);
 
-		col_pos = dict_index_get_nth_col_pos(index, sym_node->col_no);
+		col_pos = dict_index_get_nth_col_pos(index, sym_node->col_no,
+						     NULL);
 
 		if (col_pos == ULINT_UNDEFINED) {
 
diff --git a/storage/xtradb/pars/pars0pars.cc b/storage/xtradb/pars/pars0pars.cc
index f051481184b..18feb9407c7 100644
--- a/storage/xtradb/pars/pars0pars.cc
+++ b/storage/xtradb/pars/pars0pars.cc
@@ -1232,7 +1232,8 @@ pars_process_assign_list(
 		col_sym = assign_node->col;
 
 		upd_field_set_field_no(upd_field, dict_index_get_nth_col_pos(
-					       clust_index, col_sym->col_no),
+						clust_index, col_sym->col_no,
+						NULL),
 				       clust_index, NULL);
 		upd_field->exp = assign_node->val;
 
diff --git a/storage/xtradb/row/row0sel.cc b/storage/xtradb/row/row0sel.cc
index fd50e2240b5..5b85086e4a9 100644
--- a/storage/xtradb/row/row0sel.cc
+++ b/storage/xtradb/row/row0sel.cc
@@ -56,6 +56,7 @@ Created 12/19/1997 Heikki Tuuri
 #include "row0mysql.h"
 #include "read0read.h"
 #include "buf0lru.h"
+#include "srv0srv.h"
 #include "ha_prototypes.h"
 #include "srv0start.h"
 #include "m_string.h" /* for my_sys.h */
@@ -2942,9 +2943,14 @@ row_sel_store_mysql_rec(
 			: templ->rec_field_no;
 		/* We should never deliver column prefixes to MySQL,
 		except for evaluating innobase_index_cond(). */
+		/* ...actually, we do want to do this in order to
+		support the prefix query optimization.
+
 		ut_ad(dict_index_get_nth_field(index, field_no)->prefix_len
 		      == 0);
 
+		...so we disable this assert. */
+
 		if (!row_sel_store_mysql_field(mysql_rec, prebuilt,
 					       rec, index, offsets,
 					       field_no, templ)) {
@@ -3037,6 +3043,8 @@ row_sel_get_clust_rec_for_mysql(
 	dberr_t		err;
 	trx_t*		trx;
 
+	srv_stats.n_sec_rec_cluster_reads.inc();
+
 	*out_rec = NULL;
 	trx = thr_get_trx(thr);
 
@@ -3693,6 +3701,7 @@ row_search_for_mysql(
 	ulint*		offsets				= offsets_;
 	ibool		table_lock_waited		= FALSE;
 	byte*		next_buf			= 0;
+	ibool		use_clustered_index		= FALSE;
 
 	rec_offs_init(offsets_);
 
@@ -4727,10 +4736,69 @@ locks_ok:
 	}
 
 	/* Get the clustered index record if needed, if we did not do the
-	search using the clustered index. */
+	search using the clustered index... */
+
+	use_clustered_index =
+		(index != clust_index && prebuilt->need_to_access_clustered);
+
+	if (use_clustered_index && srv_prefix_index_cluster_optimization
+	    && prebuilt->n_template <= index->n_fields) {
+		/* ...but, perhaps avoid the clustered index lookup if
+		all of the following are true:
+		1) all columns are in the secondary index
+		2) all values for columns that are prefix-only
+		   indexes are shorter than the prefix size
+		This optimization can avoid many IOs for certain schemas.
+		*/
+		ibool row_contains_all_values = TRUE;
+		int i;
+		for (i = 0; i < prebuilt->n_template; i++) {
+			/* Condition (1) from above: is the field in the
+			index (prefix or not)? */
+			mysql_row_templ_t* templ =
+				prebuilt->mysql_template + i;
+			ulint secondary_index_field_no =
+				templ->rec_prefix_field_no;
+			if (secondary_index_field_no == ULINT_UNDEFINED) {
+				row_contains_all_values = FALSE;
+				break;
+			}
+			/* Condition (2) from above: if this is a
+			prefix, is this row's value size shorter
+			than the prefix? */
+			if (templ->rec_field_is_prefix) {
+				ulint record_size = rec_offs_nth_size(
+					offsets,
+					secondary_index_field_no);
+				const dict_field_t *field =
+					dict_index_get_nth_field(
+						index,
+						secondary_index_field_no);
+				ut_a(field->prefix_len > 0);
+				if (record_size >= field->prefix_len) {
+					row_contains_all_values = FALSE;
+					break;
+				}
+			}
+		}
+		/* If (1) and (2) were true for all columns above, use
+		rec_prefix_field_no instead of rec_field_no, and skip
+		the clustered lookup below. */
+		if (row_contains_all_values) {
+			for (i = 0; i < prebuilt->n_template; i++) {
+				mysql_row_templ_t* templ =
+					prebuilt->mysql_template + i;
+				templ->rec_field_no =
+					templ->rec_prefix_field_no;
+				ut_a(templ->rec_field_no != ULINT_UNDEFINED);
+			}
+			use_clustered_index = FALSE;
+			srv_stats.n_sec_rec_cluster_reads_avoided.inc();
+		}
+	}
+
+	if (use_clustered_index) {
 
-	if (index != clust_index && prebuilt->need_to_access_clustered) {
- 
 requires_clust_rec:
 		ut_ad(index != clust_index);
 		/* We use a 'goto' to the preceding label if a consistent
diff --git a/storage/xtradb/srv/srv0mon.cc b/storage/xtradb/srv/srv0mon.cc
index 7be25966557..44e228dc523 100644
--- a/storage/xtradb/srv/srv0mon.cc
+++ b/storage/xtradb/srv/srv0mon.cc
@@ -309,6 +309,18 @@ static monitor_info_t	innodb_counter_info[] =
 	 MONITOR_EXISTING | MONITOR_DEFAULT_ON),
 	 MONITOR_DEFAULT_START, MONITOR_OVLD_PAGES_READ},
 
+	{"buffer_index_sec_rec_cluster_reads", "buffer",
+	 "Number of secondary record reads triggered cluster read",
+	 static_cast<monitor_type_t>(
+	 MONITOR_EXISTING | MONITOR_DEFAULT_ON),
+	 MONITOR_DEFAULT_START, MONITOR_OVLD_INDEX_SEC_REC_CLUSTER_READS},
+
+	{"buffer_index_sec_rec_cluster_reads_avoided", "buffer",
+	 "Number of secondary record reads avoided triggering cluster read",
+	 static_cast<monitor_type_t>(
+	 MONITOR_EXISTING | MONITOR_DEFAULT_ON),
+	 MONITOR_DEFAULT_START, MONITOR_OVLD_INDEX_SEC_REC_CLUSTER_READS_AVOIDED},
+
 	{"buffer_data_reads", "buffer",
 	 "Amount of data read in bytes (innodb_data_reads)",
 	 static_cast<monitor_type_t>(
@@ -1646,6 +1658,16 @@ srv_mon_process_existing_counter(
 		value = stat.n_pages_read;
 		break;
 
+	/* Number of times secondary index lookup triggered cluster lookup */
+	case MONITOR_OVLD_INDEX_SEC_REC_CLUSTER_READS:
+		value = srv_stats.n_sec_rec_cluster_reads;
+		break;
+	/* Number of times prefix optimization avoided triggering cluster
+	lookup */
+	case MONITOR_OVLD_INDEX_SEC_REC_CLUSTER_READS_AVOIDED:
+		value = srv_stats.n_sec_rec_cluster_reads_avoided;
+		break;
+
 	/* innodb_data_reads, the total number of data reads */
 	case MONITOR_OVLD_BYTE_READ:
 		value = srv_stats.data_read;
diff --git a/storage/xtradb/srv/srv0srv.cc b/storage/xtradb/srv/srv0srv.cc
index a6035bdaa6c..60271f22dcd 100644
--- a/storage/xtradb/srv/srv0srv.cc
+++ b/storage/xtradb/srv/srv0srv.cc
@@ -490,6 +490,10 @@ UNIV_INTERN ulint	srv_fast_shutdown	= 0;
 /* Generate a innodb_status.<pid> file */
 UNIV_INTERN ibool	srv_innodb_status	= FALSE;
 
+/* Optimize prefix index queries to skip cluster index lookup when possible */
+/* Enables or disables this prefix optimization.  Disabled by default. */
+UNIV_INTERN my_bool	srv_prefix_index_cluster_optimization = 0;
+
 /* When estimating number of different key values in an index, sample
 this many index pages, there are 2 ways to calculate statistics:
 * persistent stats that are calculated by ANALYZE TABLE and saved
@@ -1960,6 +1964,11 @@ srv_export_innodb_status(void)
 	}
 #endif /* UNIV_DEBUG */
 
+	export_vars.innodb_sec_rec_cluster_reads =
+		srv_stats.n_sec_rec_cluster_reads;
+	export_vars.innodb_sec_rec_cluster_reads_avoided =
+		srv_stats.n_sec_rec_cluster_reads_avoided;
+
 	mutex_exit(&srv_innodb_monitor_mutex);
 }
 
diff --git a/storage/xtradb/trx/trx0rec.cc b/storage/xtradb/trx/trx0rec.cc
index a698b37c2a6..4d3458ff8bb 100644
--- a/storage/xtradb/trx/trx0rec.cc
+++ b/storage/xtradb/trx/trx0rec.cc
@@ -781,7 +781,8 @@ trx_undo_page_report_modify(
 				}
 
 				pos = dict_index_get_nth_col_pos(index,
-								 col_no);
+								 col_no,
+								 NULL);
 				ptr += mach_write_compressed(ptr, pos);
 
 				/* Save the old value of field */