diff --git a/doc/macports.conf.5 b/doc/macports.conf.5
index ec5fcac4f0..092405648a 100644
--- a/doc/macports.conf.5
+++ b/doc/macports.conf.5
@@ -343,7 +343,7 @@ lt lt.
 T{
 \fBRegular architectures include:\fR
 T}:T{
-ppc, i386, ppc64, x86_64, arm64
+ppc, ppc7400, ppc64, i386, x86_64, arm64
 T}
 T{
 \fBDefault (11 and later):\fR
@@ -376,7 +376,7 @@ lt lt.
 T{
 \fBRegular architectures include:\fR
 T}:T{
-ppc, i386, ppc64, x86_64, arm64
+ppc, ppc7400, ppc64, i386, x86_64, arm64
 T}
 T{
 \fBDefault (11 and later):\fR
diff --git a/doc/macports.conf.5.txt b/doc/macports.conf.5.txt
index a00e351ab9..3404f85a57 100644
--- a/doc/macports.conf.5.txt
+++ b/doc/macports.conf.5.txt
@@ -124,7 +124,7 @@ keeplogs::
 
 build_arch::
     The machine architecture to try to build for in normal use.
-    *Regular architectures include:*;; ppc, i386, ppc64, x86_64, arm64
+    *Regular architectures include:*;; ppc, ppc7400, ppc64, i386, x86_64, arm64
     *Default (11 and later):*;; arm64 or x86_64 depending on hardware
     *Default (10.6-10.15):*;; x86_64 or i386 depending on hardware
     *Default (10.5 and earlier):*;; i386 or ppc depending on hardware
@@ -133,7 +133,7 @@ universal_archs::
     The machine architectures to use for +universal variant (multiple
     architecture entries should be space separated). Should contain at
     least two entries, or be empty to disable universal building.
-    *Regular architectures include:*;; ppc, i386, ppc64, x86_64, arm64
+    *Regular architectures include:*;; ppc, ppc7400, ppc64, i386, x86_64, arm64
     *Default (11 and later):*;; arm64 x86_64
     *Default (10.6-10.13):*;; x86_64 i386
     *Default (10.5 and earlier):*;; i386 ppc
diff --git a/doc/portfile.7 b/doc/portfile.7
index 2fb68ae160..49e3efc3c9 100644
--- a/doc/portfile.7
+++ b/doc/portfile.7
@@ -230,6 +230,7 @@ Archs currently supported by macOS are:
 .Em i386 ,
 .Em ppc ,
 .Em ppc64 ,
+.Em ppc7400 ,
 and
 .Em x86_64 .
 If this option is not set, it is assumed that the port can build for all
@@ -255,10 +256,10 @@ In this case, the port will be built in 32-bit mode.
 .Em optional
 .br
 .Sy Values:
-.Em i386 x86_64 ppc ppc64 noarch
+.Em arm64 i386 x86_64 ppc ppc7400 ppc64 noarch
 .br
 .Sy Default:
-.Em i386 x86_64 ppc ppc64
+.Em arm64 i386 x86_64 ppc ppc64
 .br
 .Sy Examples:
 .Dl supported_archs i386 x86_64
diff --git a/src/macports1.0/macports.tcl b/src/macports1.0/macports.tcl
index 18109018d7..9e33d98370 100644
--- a/src/macports1.0/macports.tcl
+++ b/src/macports1.0/macports.tcl
@@ -1142,7 +1142,11 @@ match macports.conf.default."
                 }
             } else {
                 if {$os_arch eq "powerpc"} {
-                    set macports::build_arch ppc
+                    if {[sysctl hw.vectorunit] == 1} {
+                        set macports::build_arch ppc7400
+                    } else {
+                        set macports::build_arch ppc
+                    }
                 } else {
                     set macports::build_arch i386
                 }
diff --git a/src/port1.0/portconfigure.tcl b/src/port1.0/portconfigure.tcl
index 8d034b5500..50359f81e6 100644
--- a/src/port1.0/portconfigure.tcl
+++ b/src/port1.0/portconfigure.tcl
@@ -420,10 +420,10 @@ proc portconfigure::choose_supported_archs {archs} {
         } elseif {[vercmp ${configure.sdk_version} 10.6] >= 0} {
             set sdk_archs [list x86_64 i386 ppc]
         } elseif {[vercmp ${configure.sdk_version} 10.5] >= 0} {
-            set sdk_archs [list x86_64 i386 ppc ppc64]
+            set sdk_archs [list x86_64 i386 ppc ppc7400 ppc64]
         } else {
             # 10.4u
-            set sdk_archs [list i386 ppc ppc64]
+            set sdk_archs [list i386 ppc ppc7400 ppc64]
         }
 
         # Set intersection_archs to the intersection of what's supported by
@@ -456,20 +456,25 @@ proc portconfigure::choose_supported_archs {archs} {
     # e.g. if build_arch is x86_64 it's still possible to build a port
     # that sets supported_archs to "i386 ppc" if the SDK allows it.
     array set arch_demotions [list \
-                                arm64 x86_64 \
-                                x86_64 i386 \
-                                ppc64 ppc \
-                                i386 ppc]
+                                arm64 {x86_64} \
+                                x86_64 {i386} \
+                                ppc64 {ppc7400 ppc} \
+                                ppc7400 {ppc} \
+                                i386 {ppc}]
     foreach arch $archs {
         if {$arch in $intersection_archs} {
-            set add_arch $arch
-        } elseif {[info exists arch_demotions($arch)] && $arch_demotions($arch) in $intersection_archs} {
-            set add_arch $arch_demotions($arch)
-        } else {
-            continue
-        }
-        if {$add_arch ni $ret} {
-            lappend ret $add_arch
+            if {$arch ni $ret} {
+                lappend ret $arch
+            }
+        } elseif {[info exists arch_demotions($arch)]} {
+            foreach demoted_arch $arch_demotions($arch) {
+                if {$demoted_arch in $intersection_archs} {
+                    if {$demoted_arch ni $ret} {
+                        lappend ret $demoted_arch
+                    }
+                    break
+                }
+            }
         }
     }
     return $ret
@@ -487,7 +492,16 @@ proc portconfigure::configure_get_archflags {tool} {
         if {[arch_flag_supported ${configure.compiler}] &&
             $tool in {cc cxx objc objcxx}
         } then {
-            set flags "-arch ${configure.build_arch}"
+            # ppc7400 is PPC + Altivec; it's up to the ports to declare support
+            # for the ppc7400 architecture and to enable/disable Altivec. At the
+            # compiler level, this is done with -maltivec/-mno-altivec, but
+            # projects often have separate compilation paths for Altivec, so
+            # leave these top-level flags alone.
+            if {${configure.build_arch} eq "ppc7400"} {
+                set flags "-arch ppc"
+            } else {
+                set flags "-arch ${configure.build_arch}"
+            }
         } elseif {${configure.build_arch} in [list arm64 ppc64 x86_64]} {
             set flags "-m64"
         } elseif {${configure.compiler} ne "gcc-3.3"} {
@@ -1290,7 +1304,9 @@ proc portconfigure::get_compiler_fallback {} {
     set compilers ""
     lappend compilers {*}${system_compilers}
     # when building for PowerPC architectures, prefer GCC to Clang
-    if {[option configure.build_arch] eq "ppc" || [option configure.build_arch] eq "ppc64"} {
+    if {[option configure.build_arch] eq "ppc" ||
+        [option configure.build_arch] eq "ppc7400" ||
+        [option configure.build_arch] eq "ppc64"} {
         lappend compilers {*}${gcc_compilers}
         lappend compilers {*}${clang_compilers}
     } else {
diff --git a/src/port1.0/portlint.tcl b/src/port1.0/portlint.tcl
index 468cef3d82..1c53b9b1ad 100644
--- a/src/port1.0/portlint.tcl
+++ b/src/port1.0/portlint.tcl
@@ -412,6 +412,7 @@ proc portlint::lint_main {args} {
                 arm64 arm
                 intel i386
                 ppc powerpc
+                ppc7400 powerpc
                 ppc64 powerpc
                 x86_64 i386
             } {
diff --git a/src/port1.0/portmain.tcl b/src/port1.0/portmain.tcl
index 23bb4ef6ca..e63b8ec015 100644
--- a/src/port1.0/portmain.tcl
+++ b/src/port1.0/portmain.tcl
@@ -118,8 +118,8 @@ default distname {${name}-${version}}
 default worksrcdir {$distname}
 default filespath {[file join $portpath [join $filesdir]]}
 default worksrcpath {[file join $workpath [join $worksrcdir]]}
-# empty list means all archs are supported
-default supported_archs {}
+# Exclude ppc7400, which is an opt-in architecture
+default supported_archs {ppc ppc64 i386 x86_64 arm64}
 default depends_skip_archcheck {}
 default add_users {}