First try on fixing build on Mac.

Configure.pl

@@ -430,6 +430,10 @@ sub uniq {
 push @ldflags, $ENV{LDFLAGS}         if $ENV{LDFLAGS};
 $config{ldflags} = join ' ', @ldflags;
 
+# Switch shared lib compiler flags in relocatable case.
+$config{moarshared} = $config{moarshared_relocatable}   if not $args{'no-relocatable'};
+$config{moarshared} = $config{moarshared_norelocatable} if     $args{'no-relocatable'};
+
 # setup library names
 $config{moarlib} = sprintf $config{lib}, $NAME;
 $config{moardll} = sprintf $config{dll}, $NAME;

build/setup.pm

@@ -132,11 +132,12 @@ our %TC_POSIX = (
     ldsys => undef,
     ldimp => undef,
 
-    ccshared            => '-fPIC',
-    ldshared            => '-shared @ccshared@',
-    moarshared          => '',
-    ldrpath             => '-Wl,-rpath,"/@libdir@"',
-    ldrpath_relocatable => '-Wl,-z,origin,-rpath,\'$$ORIGIN/../lib\'',
+    ccshared                 => '-fPIC',
+    ldshared                 => '-shared @ccshared@',
+    moarshared_norelocatable => '',
+    moarshared_relocatable   => '',
+    ldrpath                  => '-Wl,-rpath,"/@libdir@"',
+    ldrpath_relocatable      => '-Wl,-z,origin,-rpath,\'$$ORIGIN/../lib\'',
 
     arflags => 'rcs',
     arout   => '',
@@ -215,11 +216,12 @@ our %TC_MSVC = (
     ldsys => undef,
     ldimp => '%s.dll.lib',
 
-    ccshared            => '',
-    ldshared            => '/dll',
-    moarshared          => '/implib:@moardll@.lib',
-    ldrpath             => '',
-    ldrpath_relocatable => '',
+    ccshared                 => '',
+    ldshared                 => '/dll',
+    moarshared_norelocatable => '/implib:@moardll@.lib',
+    moarshared_relocatable   => '/implib:@moardll@.lib',
+    ldrpath                  => '',
+    ldrpath_relocatable      => '',
 
     arflags => '/nologo',
     arout   => '/out:',
@@ -448,13 +450,14 @@ our %OS_MINGW32 = (
     dll   => '%s.dll',
     ldimp => '-l%s.dll',
 
-    libdir              => '@bindir@',
-    ccshared            => '',
-    ldshared            => '-shared -Wl,--out-implib,lib$(notdir $@).a',
-    moarshared          => '',
-    ldrpath             => '',
-    ldrpath_relocatable => '',
-    sharedlib           => 'lib@moardll@.a',
+    libdir                   => '@bindir@',
+    ccshared                 => '',
+    ldshared                 => '-shared -Wl,--out-implib,lib$(notdir $@).a',
+    moarshared_norelocatable => '',
+    moarshared_relocatable   => '',
+    ldrpath                  => '',
+    ldrpath_relocatable      => '',
+    sharedlib                => 'lib@moardll@.a',
 
     translate_newline_output => 1,
 
@@ -572,10 +575,12 @@ our %OS_DARWIN = (
 
     dll => 'lib%s.dylib',
 
-    ccshared   => '',
-    ldshared   => '-dynamiclib',
-    moarshared => '-install_name "@prefix@/lib/libmoar.dylib"',
-    sharedlib  => 'libmoar.dylib',
+    sharedlib                => 'libmoar.dylib',
+    ccshared                 => '',
+    ldshared                 => '-dynamiclib',
+    moarshared_norelocatable => '-install_name "@prefix@/lib/libmoar.dylib"',
+    moarshared_relocatable   => '-install_name @rpath/libmoar.dylib',
+    ldrpath_relocatable      => '-Wl,-rpath,@executable_path/../lib',
 
     -thirdparty => {
         uv => { %TP_UVDUMMY, objects => '$(UV_DARWIN)' },