diff --git a/doc/macports.conf.5 b/doc/macports.conf.5
index bd9d53df4b..deb896e201 100644
--- a/doc/macports.conf.5
+++ b/doc/macports.conf.5
@@ -301,6 +301,21 @@ T}
 .sp 1
 .RE
 .PP
+indexjobs
+.RS 4
+Number of threads to use when indexing ports\&. 0 is a special value meaning "the number of CPU cores\&."
+.TS
+tab(:);
+lt lt.
+T{
+\fBDefault:\fR
+T}:T{
+0
+T}
+.TE
+.sp 1
+.RE
+.PP
 portautoclean
 .RS 4
 Automatic cleaning of the build directory of a given port after it has been installed\&.
diff --git a/doc/macports.conf.5.txt b/doc/macports.conf.5.txt
index 9eb6295734..14543d5e67 100644
--- a/doc/macports.conf.5.txt
+++ b/doc/macports.conf.5.txt
@@ -113,6 +113,11 @@ buildmakejobs::
     physical memory plus one, whichever is less."
     *Default:*;; 0
 
+indexjobs::
+    Number of threads to use when indexing ports. 0 is a special value meaning
+    "the number of CPU cores."
+    *Default:*;; 0
+
 portautoclean::
     Automatic cleaning of the build directory of a given port after it has been
     installed.
diff --git a/doc/macports.conf.in b/doc/macports.conf.in
index 590b7414c0..9302a7810a 100644
--- a/doc/macports.conf.in
+++ b/doc/macports.conf.in
@@ -127,6 +127,11 @@ variants_conf       	@MPCONFIGDIR_EXPANDED@/variants.conf
 # - gigabytes of physical memory + 1
 #buildmakejobs       	0
 
+# Number of threads to use when indexing ports. If set
+# to 0, the number of threads will be the number of
+# automatically-detected CPU cores
+#indexjobs       	0
+
 # umask value to use when a port installs its files.
 #destroot_umask      	022
 
diff --git a/src/macports1.0/macports.tcl b/src/macports1.0/macports.tcl
index 4f0513317d..8ed5946dc5 100644
--- a/src/macports1.0/macports.tcl
+++ b/src/macports1.0/macports.tcl
@@ -56,6 +56,7 @@ namespace eval macports {
         startupitem_autostart startupitem_type startupitem_install \
         place_worksymlink xcodeversion xcodebuildcmd xcodecltversion xcode_license_unaccepted \
         configureccache ccache_size configuredistcc configurepipe buildnicevalue buildmakejobs \
+        indexjobs \
         universal_archs build_arch macosx_sdk_version macosx_deployment_target \
         macportsuser proxy_override_env proxy_http proxy_https proxy_ftp proxy_rsync proxy_skip \
         master_site_local patch_site_local archive_site_local buildfromsource \
@@ -81,6 +82,7 @@ namespace eval macports {
         rsync_server rsync_options rsync_dir startupitem_autostart startupitem_type startupitem_install \
         place_worksymlink macportsuser sudo_user \
         configureccache ccache_dir ccache_size configuredistcc configurepipe buildnicevalue buildmakejobs \
+        indexjobs \
         applications_dir applications_dir_frozen current_phase frameworks_dir frameworks_dir_frozen \
         developer_dir universal_archs build_arch os_arch os_endian os_version os_major os_minor \
         os_platform os_subplatform macos_version macos_version_major macosx_version macosx_sdk_version \
@@ -950,6 +952,7 @@ proc mportinit {{up_ui_options {}} {up_options {}} {up_variations {}}} {
         macports::configurepipe \
         macports::buildnicevalue \
         macports::buildmakejobs \
+        macports::indexjobs \
         macports::host_blacklist \
         macports::preferred_hosts \
         macports::keeplogs \
@@ -1538,6 +1541,9 @@ match macports.conf.default."
     if {![info exists buildmakejobs]} {
         set buildmakejobs 0
     }
+    if {![info exists indexjobs]} {
+        set indexjobs 0
+    }
 
     # default user to run as when privileges can be dropped
     if {![info exists macportsuser]} {
@@ -6584,12 +6590,32 @@ proc macports::get_parallel_jobs {{mem_restrict yes}} {
     variable buildmakejobs; variable os_platform
     if {[string is integer -strict $buildmakejobs] && $buildmakejobs > 0} {
         set jobs $buildmakejobs
-    } elseif {$os_platform eq "darwin" && $buildmakejobs == 0
-              && ![catch {sysctl hw.activecpu} cpus]} {
+    } else {
+        set jobs [macports::calc_auto_max_jobs $mem_restrict]
+    }
+    return $jobs
+}
+
+# Get actual number of parallel jobs based on indexjobs, which may
+# be 0 for automatic selection.
+proc macports::get_index_jobs {{mem_restrict no}} {
+    variable indexjobs; variable os_platform
+    if {[string is integer -strict $indexjobs] && $indexjobs > 0} {
+        set jobs $indexjobs
+    } else {
+        set jobs [macports::calc_auto_max_jobs $mem_restrict]
+    }
+    return $jobs
+}
+
+# Calculate jobs based on automatic selection.
+proc macports::calc_auto_max_jobs {{mem_restrict yes}} {
+    variable os_platform
+    if {$os_platform eq "darwin" && ![catch {sysctl hw.activecpu} cpus]} {
         set jobs $cpus
-        if {$mem_restrict && ![catch {sysctl hw.memsize} memsize]
-                && $jobs > $memsize / (1024 * 1024 * 1024) + 1} {
-            set jobs [expr {$memsize / (1024 * 1024 * 1024) + 1}]
+        if {$mem_restrict && ![catch {sysctl hw.memsize} memsize]} {
+            set memsize_gb [expr {($memsize / round(pow(1024,3))) + 1}]
+            set jobs [expr min($jobs, $memsize_gb)]
         }
     } else {
         set jobs 2
diff --git a/src/port/portindex.tcl b/src/port/portindex.tcl
index 1ef9502676..a71cfa240a 100644
--- a/src/port/portindex.tcl
+++ b/src/port/portindex.tcl
@@ -211,7 +211,7 @@ proc init_threads {} {
         append worker_init_script \
             [list set oldmtime $oldmtime] \n
     }
-    set maxjobs [macports::get_parallel_jobs no]
+    set maxjobs [macports::get_index_jobs]
     set poolid [tpool::create -minworkers 1 -maxworkers $maxjobs -initcmd $worker_init_script]
     set pending_jobs [dict create]
     set nextjobnum 0