diff --git a/README.md b/README.md
index c5f1a2b78..e488bc117 100644
--- a/README.md
+++ b/README.md
@@ -110,12 +110,22 @@ For detailed installation instructions, see the
 ### pip
 
 Using pip, spaCy releases are available as source packages and binary wheels (as
-of `v2.0.13`).
+of `v2.0.13`). Before you install spaCy and its dependencies, make sure that
+`pip` and `setuptools` are up to date.
 
 ```bash
+pip install -U pip setuptools
 pip install spacy
 ```
 
+For installation on python 3.5 where binary wheels are not provided for the most
+recent versions of the dependencies, you can prefer older binary wheels over
+newer source packages with `--prefer-binary`:
+
+```bash
+pip install spacy --prefer-binary
+```
+
 To install additional data tables for lemmatization and normalization in
 **spaCy v2.2+** you can run `pip install spacy[lookups]` or install
 [`spacy-lookups-data`](https://github.com/explosion/spacy-lookups-data)
diff --git a/azure-pipelines.yml b/azure-pipelines.yml
index 991d4cc33..95a76abcd 100644
--- a/azure-pipelines.yml
+++ b/azure-pipelines.yml
@@ -51,15 +51,15 @@ jobs:
         imageName: 'macos-10.14'
         python.version: '3.6'
       # Don't test on 3.7 for now to speed up builds
-      # Python37Linux:
-      #   imageName: 'ubuntu-16.04'
-      #   python.version: '3.7'
-      # Python37Windows:
-      #   imageName: 'vs2017-win2016'
-      #   python.version: '3.7'
-      # Python37Mac:
-      #   imageName: 'macos-10.13'
-      #   python.version: '3.7'
+      Python37Linux:
+        imageName: 'ubuntu-16.04'
+        python.version: '3.7'
+      Python37Windows:
+        imageName: 'vs2017-win2016'
+        python.version: '3.7'
+      Python37Mac:
+        imageName: 'macos-10.14'
+        python.version: '3.7'
       Python38Linux:
         imageName: 'ubuntu-16.04'
         python.version: '3.8'
@@ -69,6 +69,15 @@ jobs:
       Python38Mac:
         imageName: 'macos-10.14'
         python.version: '3.8'
+      Python39Linux:
+        imageName: 'ubuntu-16.04'
+        python.version: '3.9'
+      Python39Windows:
+        imageName: 'vs2017-win2016'
+        python.version: '3.9'
+      Python39Mac:
+        imageName: 'macos-10.14'
+        python.version: '3.9'
     maxParallel: 4
   pool:
     vmImage: $(imageName)
@@ -80,12 +89,12 @@ jobs:
       architecture: 'x64'
 
   - script: |
-      python -m pip install -U setuptools
+      python -m pip install -U pip setuptools
       pip install -r requirements.txt --prefer-binary
     displayName: 'Install dependencies'
 
   - script: |
-      python setup.py build_ext --inplace
+      python setup.py build_ext --inplace -j 2
       python setup.py sdist --formats=gztar
     displayName: 'Compile and build sdist'
 
@@ -94,9 +103,12 @@ jobs:
       contents: 'spacy'
     displayName: 'Delete source directory'
 
-  - bash: |
+  - script: |
       pip freeze > installed.txt
       pip uninstall -y -r installed.txt
+    displayName: 'Uninstall all packages'
+
+  - bash: |
       SDIST=$(python -c "import os;print(os.listdir('./dist')[-1])" 2>&1)
       pip install dist/$SDIST --only-binary :all:
     displayName: 'Install from sdist'
diff --git a/pyproject.toml b/pyproject.toml
index fe66494ff..c5cc5a06c 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,11 +1,10 @@
 [build-system]
 requires = [
     "setuptools",
-    "wheel",
     "cython>=0.25",
     "cymem>=2.0.2,<2.1.0",
     "preshed>=3.0.2,<3.1.0",
     "murmurhash>=0.28.0,<1.1.0",
-    "thinc==7.4.1",
+    "thinc>=7.4.1,<7.5.0",
 ]
 build-backend = "setuptools.build_meta"
diff --git a/requirements.txt b/requirements.txt
index 367eef111..91996b261 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,8 +1,9 @@
 # Our libraries
 cymem>=2.0.2,<2.1.0
 preshed>=3.0.2,<3.1.0
-thinc==7.4.1
-blis>=0.4.0,<0.5.0
+thinc>=7.4.1,<7.5.0
+blis>=0.4.0,<0.8.0; python_version >= "3.6"
+blis>=0.4.0,<0.5.0; python_version < "3.6"
 murmurhash>=0.28.0,<1.1.0
 wasabi>=0.4.0,<1.1.0
 srsly>=1.0.2,<1.1.0
diff --git a/setup.cfg b/setup.cfg
index 9bd45d45d..8e40a7afd 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -23,6 +23,7 @@ classifiers =
     Programming Language :: Python :: 3.6
     Programming Language :: Python :: 3.7
     Programming Language :: Python :: 3.8
+    Programming Language :: Python :: 3.9
     Topic :: Scientific/Engineering
 
 [options]
@@ -32,20 +33,20 @@ scripts =
     bin/spacy
 python_requires = >=2.7,!=3.0.*,!=3.1.*,!=3.2.*,!=3.3.*,!=3.4.*
 setup_requires =
-    wheel
     cython>=0.25
     # We also need our Cython packages here to compile against
     cymem>=2.0.2,<2.1.0
     preshed>=3.0.2,<3.1.0
     murmurhash>=0.28.0,<1.1.0
-    thinc==7.4.1
+    thinc>=7.4.1,<7.5.0
 install_requires =
     # Our libraries
     murmurhash>=0.28.0,<1.1.0
     cymem>=2.0.2,<2.1.0
     preshed>=3.0.2,<3.1.0
-    thinc==7.4.1
-    blis>=0.4.0,<0.5.0
+    thinc>=7.4.1,<7.5.0
+    blis>=0.4.0,<0.8.0; python_version >= "3.6"
+    blis>=0.4.0,<0.5.0; python_version < "3.6"
     wasabi>=0.4.0,<1.1.0
     srsly>=1.0.2,<1.1.0
     catalogue>=0.0.7,<1.1.0