After quite a bit of frustration with qmake, I have found what I think is the answer to your question. If not, then I have learned the way that I will use qmake until I find something better, because this is still a little bit ugly. I set up a demo project, this is my directory structure (files have extensions, folders do not):

MyProj
    MyProj.pro
    myproj-core
        myproj-core.pro
        globals.h
        MyProjCore.h
        MyProjCore.cpp
    myproj-app
        myproj-app.pro
        main.cpp

We start with MyProj.pro as a subdirs project, which is the key to doing what you ask. Basically, instead of depending on other projects to specify debug/release and all sorts of other junk, you just set it on the one qmake file. It doesn t let you make only what you need, but it s the best solution I could come up with. Here are the contents:

TEMPLATE = subdirs
# Needed to ensure that things are built right, which you have to do yourself :(
CONFIG += ordered

# All the projects in your application are sub-projects of your solution
SUBDIRS = myproj-core 
          myproj-app

# Use .depends to specify that a project depends on another.
myproj-app.depends = myproj-core

myproj-core.pro is your typical shared object library:

QT -= gui
TARGET = myproj-core
TEMPLATE = lib
DEFINES += MYPROJCORE_LIBRARY
SOURCES += MyProjCore.cpp
HEADERS += MyProjCore.h 
           globals.h

myproj-app.pro is consumer application, where the little rebuild-when-needed trick is:

QT       -= gui

TARGET = myproj-app
CONFIG   += console
CONFIG   -= app_bundle

TEMPLATE = app

# Specify that we re lookin in myproj-core.  Realistically, this should be put
# in some configuration file
INCLUDEPATH += ../myproj-core
# Link to the library generated by the project.  Could use variables or
# something here to make it more bulletproof
LIBS += ../myproj-core/libmyproj-core.so
# Specify that we depend on the library (which, logically would be implicit from
# the fact that we are linking to it)
PRE_TARGETDEPS += ../myproj-core/libmyproj-core.so

SOURCES += main.cpp

I hope this solves your problem, as I know it solved mine!

EDIT: I made a file specifically for building the dependencies for me, I store it in a sibling folder of each of my projects (child of the MyProj in the directory structure specified above) called dependencies.pri:

# On windows, a shared object is a .dll
win32: SONAME=dll
else:  SONAME=so

# This function sets up the dependencies for libraries that are built with
# this project.  Specify the libraries you need to depend on in the variable
# DEPENDENCY_LIBRARIES and this will add
for(dep, DEPENDENCY_LIBRARIES) {
    #message($$TARGET depends on $$dep ($${DESTDIR}/$${dep}.$${SONAME}))
    LIBS += $${DESTDIR}/lib$${dep}.$${SONAME}
    PRE_TARGETDEPS += $${DESTDIR}/lib$${dep}.$${SONAME}
}

So at the bottom of all the consuming applications, I can add the lines:

DEPENDENCY_LIBRARIES = myproj-core

include(../config/dependencies.pri)

This assumes that you are copying the libraries to some shared location and/or moving them around as needed, so my function might not work for you, but I figured I would add it to the solution.

I use the solution below. This works without the usage of an extra .pro file with subdir template.

TEMPLATE = app
TARGET = MyApp
PRE_TARGETDEPS = ../../libs/MyLib/MyLib.a
INCLUDEPATH += ../../libs/MyLib/include 
HEADERS += src/MyApp.h 
    ../../libs/MyLib/incude/MyLib.h
SOURCES += src/MyApp.cpp
LIBS += ../../libs/MyLib/MyLib.a

MyLib.target = ../../libs/MyLib/MyLib.a
MyLib.commands = cd ../../libs/MyLib && make
MyLib.depends = ../../libs/MyLib/Makefile
QMAKE_EXTRA_TARGETS += MyLib

1. Check out this question: Force relink when building in QT Creator

2. Try adding something similar to this code to your pro file:

   CONFIG(debug, debug|release) {   
       DESTDIR = ../../../bin/debug  
       OBJECTS_DIR = ./debug  
   }  
   else {   
       DESTDIR = ../../../bin/release  
       OBJECTS_DIR = ./release  
   }
   

Then you will have to specify the dependencies for each configuration:

CONFIG(debug, debug|release) {   
    LIBS += -L../../../lib/debug   
        -L../../../bin/debug   
        -llib1   
        -llib2   
    PRE_TARGETDEPS += ../../../lib/debug/liblib1.a   
        ../../../lib/debug/liblib2.a 
else { 
    LIBS += -L../../../lib/release 
        -L../../../bin/release 
        -llib1   
        -llib2   
    PRE_TARGETDEPS += ../../../lib/release/liblib1.a 
        ../../../lib/release/liblib2.a 
}

I had this problem when refactoring my project, after I moved in a new DLL (pqXDot) a reusable class (from pqGraphviz).

After adding a new DLL to my project, and adding the new DLL reference to others DLL and applications that needed it, I had in main .pro:

TEMPLATE = subdirs

SUBDIRS += 
    pqConsole 
    pqConsoleTest 
    pqSource 
    pqSourceTest 
    fdqueens 
    pqGraphviz 
    pqGraphvizTest 
    pqXDot

and the rebuild caused a linker error, because pqGraphviz, the DLL being restructured, can t find pqXDot, the new DLL.

It turns out it s sufficient to reorder the SUBDIRS list, moving the required DLL before the dependent one:

SUBDIRS += 
    pqConsole 
    pqConsoleTest 
    pqSource 
    pqSourceTest 
    fdqueens 
    pqXDot 
    pqGraphviz 
    pqGraphvizTest

For those that are interested into a template for your Qt/QML project, I have published one template on GitHub QmlAppTemplate.